Forum:Reasons why cards are Forbidden/Limited/List

List of Reasons for Why Cards are Forbidden/Limited
Card Name	Reasons
Forbidden
Amazoness Archer	Banned due to causing FTK's due to their lack of "once per turn" restriction, similar to Mass Driver (also Forbidden; see below). They are also searchable, with M-X-Saber Invoker (also Forbidden) being able to search Archer, and Gear Gigant X being able to search the two level 4 Cannon Soldiers (and Toon Table of Contents can get Toon Cannon Soldier). All of these are Unlimited in the TCG.
Cannon Soldier
Cannon Soldier MK-2
Toon Cannon Soldier
Ancient Fairy Dragon	Can destroy all Field Spell cards on the field, give you 1000 free LP, and then search another from the Deck. Easily summoned and looped via Destrudo and Recycle, respectively. Several Field Spells can exploit this, such as Future Visions creating a Normal Summon lockdown, Divine Wind of Mist Valley causing loops with Genex Blastfan and Ally Birdman for an FTK, and SPYRAL Resort (Limited) netting multiple searches within the same turn. Also permits 1 free Special Summon of a Level 4 or lower monster from your hand per turn, though you cannot attack if you do so.
Astrograph Sorcerer	Generates outrageous pluses for Pendulums. Insanely busted with Heavymetalfoes Electrumite. Being a Level 7 allows easy access to Odd-Eyes Absolute Dragon, which leads into Odd-Eyes Vortex Dragon. Hit due to the dominance of Pendulum Magician decks in the TCG metagame. This card is Limited in the OCG.
Blackwing - Gofu the Vague Shadow	Level 5 tuner with a Cyber Dragon-like effect. Special Summons two tokens when it's Summoned by its own condition, which were used as materials for Metalfoes Fusion Monsters, while this card allowed for easy plays into Ultimaya Tzolkin, which allows easy Summons of good level 7-8 Dragon Synchro Monsters such as Beelze of the Diabolic Dragons or Crystal Wing Synchro Dragon. It was swiftly Limited and then Forbidden when Link Monsters came out, due to the increased power of Tokens.
Blackwing - Steam the Cloak	Easily summoned by Crystron Halqifibrax (not yet out in the TCG, Limited in the OCG) to create card advantage for Link combos. This card is Unlimited in the TCG.
Blaster, Dragon Ruler of Infernos	Incredibly powerful Dragon monsters. Can be Special Summoned easily from the hand or Graveyard by banishing any 2 Dragon monsters and/or monsters of their same Attributes from the hand or Graveyard. Can be put into just about any Deck of their own type and/or attributes to add huge power plays and consistency. They can also search another monster of their same respective type and attribute when banished to Summon another Dragon Ruler, or when banished with Sacred Sword of Seven Stars or Gold Sarcophagus, even another copy of themselves at more than 1. The release of Number 95: Galaxy-Eyes Dark Matter Dragon (now Forbidden, see below) was likely the final nail in the coffin of these cards, as players could easily dump three of four Dragon Rulers into the Graveyard on Turn 1 when Summoning Dark Matter Dragon for an easy OTK. However, with Number 95 now banned and Gold Sarc Limited, Tempest was allowed back to 1 (see below).
Redox, Dragon Ruler of Boulders
Tidal, Dragon Ruler of Waterfalls
Cyber Jar	Destroys all monsters instantly. Unlike Morphing Jar #2, this has a set number of cards to get, allowing players to gain instant advantage easily. Swarms the field by itself and can create OTKs and can give either player crazy advantage. Can wipe out a whole field of boss monsters effortlessly. A bit slower and harder to use now with THRIO and Starlight Road in the game, but can still turn an entire game around in an instant.
Dandylion	Compulsory effect. Gives lots of advantage most of the time. Re-usable in many Decks, creates Tokens that can be used for Tribute/Synchro/Link Summoning. Effect also triggers when it enters the Graveyard through any means.
Denglong, First of the Yang Zing	Can search ANY "Yang Zing" card upon its Summoning, and due to the wide variety of Levels the "Yang Zing" monsters share, it can function as almost any necessary Tuner, while sending "Chiwen, Light of the Yang Zing" to the Graveyard to easily activate its revival effect. In addition, if it leaves the field it Special Summons another "Yang Zing" from the Deck, extending the chain of defensive monsters or Synchro/Xyz/Link Materials. Also, unlike the others, neither effect can never miss their timing, leaving few options open for the opponent to stop them from activating. The net result was often a free Nine Pillars of Yang Zing to be followed with Herald of the Arc Light for 2 negations. This card is Unlimited in the OCG.
Djinn Releaser of Rituals	Prevents your opponent from Special Summoning at all when used for a Ritual Summon, and can be banished from the Graveyard to be used for a Ritual Summon as well. While it was initially a popular card in Chaos Herald of Perfection decks (where it was easily searchable by Tour Guide From the Underworld), it was later Forbidden due to abuse in the Nekroz archetype, where it was mainly used to Ritual Summon Nekroz of Clausolas, which can search Nekroz Cycle by its own effect, which can then Ritual Summon Clausolas from the Graveyard by using Djinn. Can also be dumped with Armageddon Knight, Dark Grepher, and Lavalval Chain (Forbidden). This card is Unlimited in the OCG.
Double Iris Magician	Can search for Time Pendulumgraph and Star Pendulumgraph, causing advantage. This card is Limited in the OCG.
Eclipse Wyvern	Banishes any level 7 or higher LIGHT or DARK dragon monster from your deck when sent to the graveyard by any means, and it can add that monster to your hand when banished from the graveyard. Can easily be sent to the graveyard in most dragon decks with several cards, and could easily be milled in Lightsworn decks in the past. Can easily be banished from the grave as a cost to summon certain monsters such as the Dragon Rulers, Black Dragon Collapserpent (Limited in the TCG), Chaos Sorcerer, BLS, Lightpulsar Dragon, Darkflare Dragon, etc. Forbidden due to being abused in Thunder Dragons with Guardragon Elpy being capable of Summoning it from the Deck for easy searching, and Guardragon Pisty allowing its effect to be looped.
Elder Entity Norden	Powerful generic Fusion Monster that can revive any Level 4 or lower monster from your Graveyard for easy Rank 4 Xyz Summons or Synchro Summons with Instant Fusion, or can be used with Super Polymerization to fuse two of your opponent's Synchro or Xyz Monsters to make this card. Can be Summoned multiple times with Re-Fusion and Fusion Gate for OTKs and even FTKs. Enables draw loops when combined with Zoodiac Xyz Monsters, Fusion Substitute, Lunalight Black Sheep and Daigusto Emeral (Forbidden in the TCG), which was likely the last straw for this card.
Fairy Tail - Snow	Special Summons itself as a Quick Effect by banishing 7 other cards from the Graveyard, field or hand, being a powerful disruption card which was abusable in "Infernoid" and "Lightsworn" Decks in the past that could quickly fill the Graveyard with fodder for its effect, which turns this card into a free material for Xyz, Synchro or Link Summons, while possibly nullifying a troublesome opposing monster in the process since it sets an opponent's monster when summoned. Can be easily sent to the Graveyard with the Brilliant Fusion engine as Fusion Material for "Gem-Knight Seraphinite" or by being discarded by Danger! monster effects. Can also be used multiple times per turn, or even per Chain to mass banish cards. Thunder Dragons took this to whole new level by banishing the Thunder Dragons to gain massive advantage, which was likely the final nail in this card's coffin. This card is Unlimited in the OCG.
Firewall Dragon	Can bounce or recycle monsters from field or GY and can easily swarm the field because of a lack of once-per-turn restriction. Can start several OTK/FTK loops and is the single reason why some cards are/were on the Forbidden/Limited list at all.
Fiber Jar	Even though it's slower and harder to pull off than it once was, it resets almost everything. It even puts itself back into the Deck when flipped, even if it would be destroyed by battle. If used in a Deck with cards like Soul Release, you can slowly Banish your opponent's entire Deck, while giving them a smaller Deck each time Fiber Jar is used.
Fishborg Blaster	An infinitely-reusable Tuner, although restricted to just WATER non-tuner monsters. Can cause easy OTK's when used with cards such as Superancient Deepsea King Coelacanth. Broken with Formula Synchron and T.G. Hyper Librarian. Fishborg Launcher was designed to replace this card. With the release of Atlanteans, this card would create even more powerful combos and loops if it were to be unbanned.
Gandora-X the Dragon of Demolition	Destroys all other monsters on the field when it is summoned from the hand and can inflict damage to your opponent equal to the highest original ATK among them. However, in the OCG this card inflicts damage equal to the highest current ATK instead, allowing for easy FTKs. This card is Unlimited in the TCG.
Glow-Up Bulb	Plant Decks were still topping after being hit format after format in 2012, Konami must have decided to finally kill them. Extremely consistent in Synchro Decks. Easily recyclable through its own effect, but the effect can only be used once per Duel. This may have also been a hit to Future Fusion FTK Decks (though Future Fusion was soon Forbidden, and later errata'd to make it slower). Came off in conjunction with the decline in Plant Synchro Decks' viability in the current metagame, but was put back on again in the January 2019 OCG lists after new applications in their meta arose with Linkuriboh and Crystron Halqifibrax (which is not yet out in the TCG and Limited in the OCG). This card is Unlimited in the TCG.
Grinder Golem	Special summons two free tokens to your field when special summoned to your opponent's field by its effect, causing nasty loops in one turn with Linkuriboh, Akashic Magician, and Security Dragon to make almost any Link 4 Monster. This card is Limited in the OCG.
Guardragon Agarpain	Can special summon any dragon-type monster from your extra deck to an extra or main monster zone that 2 or more Link Monsters point to, allowing for the easy summoning of strong monsters such as Crystal Wing Synchro Dragon, Hot Red Dragon Archfiend Abyss, Borreload Savage Dragon, or even Guardragon Elpy to get access to any dragon-type monster from your main deck as well.
Heavymetalfoes Electrumite	Grants absurd and almost-unnecessary consistency to any Pendulum Deck. Can send any Pendulum Monster from Deck to Extra Deck on summon AND retrieve any Pendulum Monster from Extra Deck once per turn (including the one sent when it was summoned) by popping any other card you control, most likely a spare Pendulum Monster to immediately be Pendulum Summoned again. Link arrows are perfect for Pendulum Summoning. Also combos absurdly well with Astrograph Sorcerer and Chronograph Sorcerer (see below).
Ib the World Chalice Justiciar	Key monster in the World Chalice archetype. Can easily be Synchro Summoned by treating any World Chalice normal monster you control as a Tuner, and adds any World Legacy card from your deck to your hand upon being Synchro Summoned, most of which can wall or cancel out the effects or summons from your opponent's extra deck link monsters. It can also Special Summon any World Chalice monster from your deck when it dies. This card is Unlimited in the OCG.
Knightmare Goblin	Grants any Deck splashable access to a basically-free extra Normal Summon, kick-starting many unfair combos, including consistently achieving an Extra Link. It also protects your co-linked Monsters from being targeted. Especially potent with Firewall Dragon (see above).
Knightmare Mermaid	Can special summon any Knightmare monster from your deck by discarding 1 card when it's link summoned, which can be used to summon Knightmare Corruptor Iblee, extending and protecting Extra Link combos. Forbidden due to use in Orcust decks, where summoning Orcust Knightmare creates a powerful combo which, due to this card's easy summoning requirements, could be accessed by summoning any two monsters.
Lavalval Chain	Can easily be Xyz Summoned in Rank 4 Xyz Decks, and can also send ANY card from your Deck to the Graveyard or place any monster card from your Deck on top of your Deck. Mainly hit due to causing loops and OTK's due to its lack of a hard once per turn restriction, or possibly to pre-emptively hit the Clownblade Deck that was topping in the OCG.
Level Eater	A Level 1 monster that can revive itself any number of times per turn so long as you have a Level 5 or higher monster on your field. While it was always a popular Tool in Synchro Decks, it was barely relevant until DARK Synchro Decks with more Tuner Synchro Monsters such as Accel Synchron, Coral Dragon, Flower Cardian Moonflowerviewing, and the Assault Blackwing synchro monsters abused this card for combos including banishing the opponent's entire hand in one turn with "PSY-Framelord Omega" or "Trishula, Dragon of the Ice Barrier", summon two "Shooting Quasar Dragons" in one turn, as well as acting like near-infinite revival fodder. Easily dumped by Foolish Burial and Mathematician and searched by One for One and can also be used in Link spam decks to set up a Knightmare lock on the first turn, which makes it unlikely to ever get unbanned.
Magical Scientist	Could easily create an FTK with Catapult Turtle; however, Catapult Turtle's effect has now been errata'd to once per turn. Also, can easily lead to a swarm of Xyz or Link Monsters. Can be searched by Where Arf Thou? and some of the Prophecy/Spellbook cards.
Majespecter Unicorn - Kirin	Splashable Pendulum monster with a good effect. Can bounce 1 monster from both player's fields during either player's turn, allowing you to reuse certain cards again on your turn, or disrupt important plays during your opponent's. It is best used to bounce Performapal Skullcrobat Joker to reuse next turn. Is also immune to being targeted and destroyed by the opponent's card effects, making it hard to remove outside of battle. With the release of Link Monsters and Master Rule 4 making this card even stronger than before, its very unlikely to ever come off the list now.
Makyura the Destructor	When sent to the Graveyard, this card allows for Traps to be activated from the hand for the turn. Since this card's effect does not activate, it bypasses cards like Soul Drain and The End of Anubis. A lot of Trap Cards that have powerful effects are balanced due to the fact of them needing to wait a turn to be activated, this removes the downside. Effect sets up OTKs and FTKs that wouldn't be possible otherwise, such as Exodia deep draw FTK's, the Dark Scorpion/Makyura OTK, and Chain Material/Fusion Gate FTK's.
Master Peace, the True Dracoslaying King	Powerful boss monster that can easily be Tribute Summoned by Tributing Continuous Spell/Trap cards as well as monsters, and is unaffected by effects of cards that have the same card type as the cards Tributed for its Summon. This results in it being vulnerable to just 1 card type in particular, which your opponent may not have easy access to at that point in the duel. Can also destroy any other card on the field during either player's turn by banishing a Continuous Spell/Trap from your Graveyard, disrupting plays during your opponent's turn and clearing the way for OTK's.
Maxx "C"	Very effective hand Trap at stunning Decks that Special Summon constantly, allowing you to draw 1 card every time. When chained to an opponent's effect that can/will Special Summon, you'll lose no hand advantage. You'll gain further pluses if they decide to swarm anyway, or prematurely end their turn, leaving themselves open to a retaliatory OTK. Can also be searched by Retaliating "C", another hand Trap. This card is Unlimited in the OCG.
Mind Master	Very similar to Substitoad (who is also Forbidden), except you pay 800 LP each time (or you can use 1 more card to bypass it). Creates many OTK's/FTK's, including an attacking OTK with Reinforced Human Psychic Borg and many deep draw FTK's with Caam, Serenity of Gusto. Can be searched by Emergency Teleport and One for One.
M-X-Saber Invoker	Easy monster spam for various strong and defining decks, which lead into crazy combo extensions and OTKs by means of Xyz or Link Summons. Incredibly easy to summon with cards like Junk Forward, Marauding Captain, Psychic Wheeleder, Speedroid Terrortop (see below). Could also search out Amazoness Archer (above) to enable FTKs.
Number 16: Shock Master	Creates an immediate lock/OTK and can ruin an entire Deck, depending on what type of card they use most. Easily Summoned first turn in most Rank 4 Xyz Decks. Can outright win games if played alongside other lockdown cards.
Number 42: Galaxy Tomahawk	Special summons as many tokens as possible to your field, which allows for very easy Link Summons. This card is Unlimited in the OCG.
Number 86: Heroic Champion - Rhongomyniad	Has several overpowered effects based on the number of Xyz materials attached to it, ranging from inability to be destroyed by battle, being unaffected by card effects, preventing Summons by the opponent, and destroying all the opponent's cards on the field. This makes it literally invincible with 4 or materials, but it was viewed as impractical until the release of Number 75: Bamboozling Gossip Shadow. Summoning it with 5 materials then became easy or even 6 materials is possible. This card is Unlimited in the OCG.
Number 95: Galaxy-Eyes Dark Matter Dragon	Triple Foolish Burial for Dragons, easily summonable on top of any Rank 8 Galaxy-Eyes. Also a 4000 ATK double attacker. Mainly banned in the OCG due to it easily enabling FTKs in conjunction with Gandora-X the Dragon of Demolition. In the TCG it was abused to send Arkbrave Dragon and Amorphage Goliath to the GY and lock any opponent out of their Extra Deck on top of whatever other monsters you summoned.
Orcust Harp Horror	Key card in the Orcust archetype. Lets you Special Summon any Orcust monster from your deck by banishing itself from your graveyard, including Orcust Brass Bombard and Orcust Cymbal Skeleton, which can then Special Summon another Orcust Monster from your hand and graveyard, respectively, or Orcust Knightmare, which can send any Orcust monster from your deck to your graveyard to strengthen any monster on the field by 100 points x it's level. They can all be recycled for use again by World Legacy - "World Wand", or the Orcust link monsters, such as Orcustrion (which can make the ATK of all your opponent's monsters 0), Galatea, the Orcust Automaton (Semi-Limited in the OCG, see more on this card below), Longirsu, the Orcust Orchestrator (can send any linked monster your opponent controls to their Graveyard), or Dingirsu, the Orcust of the Evening Star, which can send any card your opponent controls to the Graveyard while also preventing your cards from being destroyed. Because they are all DARK, they can also work well with the Phantom Knights' archetype, such as by using The Phantom Knights' Rank-Up-Magic Launch to summon True King of All Calamities by using Dingirsu as Xyz Material, preventing your opponent from using any monster effects on the field during their turn. This card is Semi-Limited in the OCG.
Outer Entity Azathot	Very powerful rank 5 Xyz monster that can prevent your opponent from activating any monster effects for the rest of the turn that it is summoned. It can even be summoned during your opponent's turn for a lockdown using The Phantom Knights' Rank-Up-Magic Launch on Time Thief Redoer, or by using the effect of Tellarknight Ptolemaeus (also Forbidden, see below). It can also be summoned during your turn by using Outer Entity Nyarla as Xyz Material, and if you used a level 4 Fusion and Synchro monster to Xyz Summon Nyarla (such as Elder Entity Norden (Also Forbidden, see above) reviving a level 4 Synchro Monster with its effect), you can nuke your opponent's field.
Performage Plushfire	Too abusable. Spawns any Performage monster from your hand or Deck whenever it's destroyed without any restriction and easily recyclable by being a Pendulum Monster. Combos well with Wavering Eyes, Performapal Pendulum Sorcerer, and Luster Pendulum, the Dracoslayer (Limited in the OCG and Semi-Limited in the TCG).
Performapal Monkeyboard	Key card in Performapal Decks. Can search any Level 4 or lower Performapal Monster when it's activated as a pendulum scale, allowing you to set up both scales by itself to Pendulum Summon practically for free. Can be searched easily itself by Performapal Skullcrobat Joker (Forbidden in the TCG and Limited in the OCG), Performapal Pendulum Sorcerer, and Wavering Eyes.
Performapal Skullcrobat Joker	This card is a themed Elemental HERO Stratos (Limited in the TCG and Semi-Limited in the OCG). It can single-handedly set up a Pendulum Summon by searching Performapal Monkeyboard (Forbidden), and can search Performapal Pendulum Sorcerer to further thin the Deck and set up plays. Unlike Stratos, however, its effect requires a Normal Summon, making it far slower in the current meta. With Pendulum Magician decks topping, this card is less likely to come back. This card is Limited in the OCG.
Phoenixian Cluster Amaryllis	The effect can be used multiple times in the same End Phase, leading to an FTK loop with Topologic Bomber Dragon. Predaplant Ophrys Scorpio (Limited in the OCG), Aromaseraphy Jasmine, Lonefire Blossom (also Limited in the OCG) and Evil Thorn help to easily get the necessary 10 plant monsters into the graveyard. Can be searched by Curious, the Lightsworn Dominion.
Red-Eyes Darkness Metal Dragon	Absurdly easy to Summon, with high ATK, and can summon any Dragon from your hand or grave with no cost. Splashable in any Dragon Deck. Particularly problematic when used with Inferno Reckless Summon in Hieratics at more than 1 (which will Summon it with 0 ATK using Atum and make it IRS-legit.) Needed to be hit because most Dragon Decks were topping. Can be searched easily with Eclipse Wyvern and revived with Red-Eyes Wyvern or Lightpulsar Dragon. With the TCG release of rank 10 Xyz's such as Gustav Max and Super Dora, which are easily Summoned with two copies of this card, it stayed limited for a long time, but the releases of Gandora-X the Dragon of Demolition and Guardragons were the final nails in this card's coffin in the OCG. This card is Limited in the TCG.
Salamangreat Miragestallio	The most important monster in the Salamangreat archetype. Can Special Summon any Salamangreat monster from your deck by detaching an xyz material, and can also return a monster on the field to the hand when it is used for a Link Summon of a Salamangreat monster. Can be Xyz Summoned simply by Normal Summoning Gazelle (Limited, see below) to send Spinny from your deck to the Graveyard, which can then revive itself so you can summon this card, and Miragestallio can then Special Summon Jack Jaguar from your deck, which can then Special Summon itself from the graveyard once you Link Summon Sunlight Wolf, while returning the Miragestallio back to your extra deck, and then returning Gazelle back with Sunlight Wolf, and when you link summon using Sunlight Wolf as Material it can search any Salamangreat Spell/Trap Card, such as Salamangreat Sanctuary (which can let you use 1 Salamangreat Link Monster as the entire link material for a Salamangreat Link Summon), Salamangreat Circle (Limited in the TCG, see below) or Salamangreat Roar (can negate any card). This card is Unlimited in the OCG.
Samsara Lotus	Similar to Phoenixian Cluster Amaryllis (above), this was used in an FTK loop with Topologic Bomber Dragon, Trickstar Black Catbat and Knightmare Cerberus. This card is Unlimited in the OCG.
Substitoad	Poorly designed card, able to mill most of your Deck in one turn. No once per turn restriction. Combos well with Pot of Avarice (which is also Forbidden in the TCG). See also: Frog Burn FTK (The most consistent burn OTK/FTK Deck for the March 2010 format). Tradetoad was designed to be a fair version of it.
Summon Sorceress	Can easily grab any monster from Deck assuming it points to a monster with the same type, such as Destiny HERO - Malicious (Semi-Limited in the TCG), or any other normally unsearchable monster, for the setup of mass Link Summons. It also spawned various new FTK combos.
Supreme King Dragon Starving Venom	Copies effects, just like The Tyrant Neptune (see below), leading to FTKs by copying Lyrilusc - Independent Nightingale twice for 8000 damage. Easily summoned multiple times in Pendulum Magician decks. This card is Unlimited in the OCG.
Tellarknight Ptolemaeus	Generic Rank 4 Xyz Monster that can be made with up to 5 Level 4 monsters, and can Summon any Rank 5 Xyz Monster from your Extra Deck by detaching 3 materials and using itself as Xyz Material (and is chainable). Mainly Forbidden for being able to Summon strong monsters that shouldn't Normally be possible for most Decks, such as Constellar Pleiades, Cyber Dragon Nova (which is then used to Summon Cyber Dragon Infinity), and Outer Entity Azathot (now Forbidden, see above). Tellarknight Vatlamyus was designed to replace this card.
Tempest Magician	Can remove all spell counters from the field to inflict 500 points of damage to your opponent for each removed spell counter, causing burn FTK's if you can get 16 spell counters on the field for 8000 damage. Immediately gains one upon being summoned, and it is easy to get the other necessary 15 spell counters on the field by discarding 15 cards from your hand in deep draw FTK's using Royal Magical Library or T.G. Hyper Librarian, or when it is used with other cards that can easily rack up spell counters like Spell Power Grasp or Mastery, cards in the Endymion Archetype, Magical Exemplar, or even with 3 Spellbook Star Halls in Spellbook turbo decks (before Spellbook of Judgment was forbidden, see below). This card is Unlimited in the OCG.
The Phantom Knights of Rusty Bardiche	Can Set any Phantom Knights Spell or Trap card from your deck by sending 1 Phantom Knights monster from your Deck to the Graveyard, allowing you to search easy endboard enablers, such as The Phantom Knights' Rank-Up-Magic Launch (Forbidden in the TCG) to Xyz Summon Outer Entity Azathot on your opponent's turn or Phantom Knights' Fog Blade to stop their plays or even The Phantom Knights of Shade Brigandine to set up Time Thief Redoer, while also enabling the effects of Phantom Knights monsters such as The Phantom Knights of Ancient Cloak, to search extra Fog Blades or extenders. In Orcust decks its last effect can be abused with Dingirsu, the Orcust of the Evening Star, Orcustrated Babel and Orcust Cymbal Skeleton. Forbidden not just due to its power, but also making Phantom Knights far too splashable. This card is Unlimited in the OCG.
The Tyrant Neptune	High-Level monster with an effect similar to Phantom of Chaos (now Unlimited; see below). Was Forbidden because of an OTK with "Lyrilusc - Independent Nightingale" (which is easily Summoned by "Instant Fusion"), where you copy that card's effect with this card, which gives it 6000 ATK (5000 with its effect + 1000 from "Nightingale" itself), makes it unaffected by any other card effects, and enables it to inflict 5000 points of damage to your opponent once per turn, guaranteeing an OTK if it survives your opponent's turn. Unlike most other effect-copying monsters, Neptune is permanent, making it extremely difficult to remove. While it can be overcome by some cards such as Crystal Wing Synchro Dragon, Honest, or Kaijus, it's still terrifying to go up against otherwise. Can also be searched by King of the Feral Imps.
Thunder Dragon Colossus	A one-sided Mistake, this card is the backbone of the Thunder Dragon Deck. It can protect itself from destruction while banishing Thunder Dragons for advantage. Easy to make 3 of in a pure deck thanks to Some Summer Summoner, easy to use for Rank 8 plays and to aid the board in "Kitchen Sink" versions. This card is Limited in the OCG.
Topologic Gumblar Dragon	Can discard up to two cards per turn with its effect by discarding up to two of yours, or for free if Extra Linked. It's possible to hand loop the opponent to make them start with two or fewer cards in their hand while you have a full board before their first Main Phase 1.
Victory Dragon	Was Forbidden on principle due to being able to interact with something outside the current Duel, rather than inside. Since Victory Conditions don't count as effects, cards like Skill Drain and Forbidden Chalice are useless against it. In tournaments, an opponent could surrender or intentionally try to receive a Game Loss penalty in an attempt to lose only the Duel instead of lose the entire Match with this card's effect. Led to judge declarations involving "unsportsmanlike conduct" and major ruling hassles during the time it was playable.
Wind-Up Carrier Zenmaity	Very easy to Summon in Wind-Up Decks. Starts up and creates nasty loops such as the infamous Wind-Up Hand Loop. Takes any 2 Level 3 monsters to Summon, rather than being archetype specific. Summoning it pretty much meant you would swarm. This card is Unlimited in the OCG because Wind-Up Hunter (below) is Forbidden in the OCG.
Wind-Up Hunter	Key card of the infamous Wind-Up Hand Loop along with Wind-Up Rat and Wind-Up Carrier Zenmaity (which is Forbidden in the TCG). Can be searched by Fire Formation - Tenki and most of the Wind-Up cards. This card is Unlimited in the TCG.
Yata-Garasu	One of the very first cards to be put on the banlist. Easily prevents a player who is behind on resources from ever recovering. Under very specific circumstances, it can even prevent a player from making a move for the rest of the Duel (see Yata-Garasu Lockdown). Can be searched easily by Aratama and Tour Bus To Forbidden Realms.
Zoodiac Broadbull	Generic Rank 4 Xyz Monster that can also easily be Summoned by using any other Zoodiac monster you control as material, or simply by using any 2 Level 4 monsters you control. Can search any Beast-Warrior monster that can be Normal Summoned by detaching a material, including other Zoodiac monsters (mainly Whiptail, which can then attach itself to this card to give it 1200 ATK and banish any monster it battles), but it can also search Pendulum Scales, Fire Fists, Bujins, Gladiator Beasts, Koa'ki Meiru, and others; basically like a better Fire Formation - Tenki.
Zoodiac Drident	Strong Rank 4 Xyz Monster that can easily be Summoned by using any other Zoodiac monster you control as material, including other Zoodiac Xyz Monsters such as Chakanine or Broadbull (also Forbidden), which only require any 2 Level 4 monsters to Summon. Can destroy any face-up card on the field during either player's turn, clearing the way for OTK's or allowing disruption of cards during your opponent's turn. Mainly hit due to Zoodiac Decks dominating the metagame. This card is Limited in the OCG.
Brilliant Fusion	Abused in many decks just to get access to Gem-Knight Seraphinite, which can be summoned using ANY Light monster, and it gives you an extra Normal Summon, kick-starting many unfair combos. Was Forbidden due to overuse in Thunder Dragons for a free Thunder monster and Foolish Burial. Can be searched by Predaplant Darlingtonia Cobra after it is Special Summoned by Predaplant Ophrys Scorpio. This card is Unlimited in the OCG.
Butterfly Dagger - Elma	Creates infinite loops with Gearfried the Iron Knight, such as drawing an unlimited number of cards with Royal Magical Library(Which can either lead to you drawing the pieces of Exodia or gaining an infinite number of Life Points with Spell Absorption (which can then lead to an infinite burn loop with Fire Princess), etc. Also insanely abusable in Inzektors.
Card of Safe Return	Many Decks rely on Graveyard manipulation (such as Zombies, Wind-Up, Fabled, Dark World, Infernoid, etc.); this card can easily generate extremely high draw power when used with them without any restriction.
Change of Heart	Better than Brain Control and Mind Control. Gain an opponent's monster for free for a turn, and you can do whatever you want with it.
Chicken Game	Generic draw Spell card that can be searched by Terraforming (Semi-Limited) and reused by Pseudo Space, enabling severe Deck thinning for virtually any Deck. Mainly Forbidden due to abuse in various FTK Decks (including one with Monarchs) that used it and Upstart Goblin (below) to separate your life points from your opponent's enough to FTK using Life Equalizer (Forbidden in the OCG), Blasting the Ruins, or Magical Explosion (Limited in the TCG, Forbidden in the OCG). This card is Unlimited in the OCG.
Cold Wave	Temporarily disables ALL Spell and Trap usage for a fairly long time, which allows preparations for an OTK and can leave the opponent vulnerable and unable to defend himself or herself as once you use an effect that destroys their back row. Incredibly hard to fight against if the opponent is using a Deck that focuses on monster effects rather than Spells or Traps. Cold Feet was intended to be a fair(ly bad) version of this card.
Confiscation	Devastating 1 for 1 card with a low cost. Allows a player to see an opponent's entire hand (letting them know what Deck they may be playing and what strategies they may use next) and freely get rid of their presumably best or most useful card. Appointer of the Red Lotus was designed to be a fair version of this card.
Delinquent Duo	Very powerful 2 for 1 card with a low cost. Discards 2 cards from your opponent's hand, and they have no control over one of the cards they lose. Especially devastating when the opponent has only a few cards in their hand.
Dimension Fusion	Too many good combos. Was abused with Dark Armed Dragon to clear the opponent's field and swarm your own, forming an OTK. With more and more Decks relying on Banished monsters, this can't come back. Like Cyber-Stein (above), the outcome is worth the high cost.
Divine Sword - Phoenix Blade	Provides free discard fodder for Knightmare monsters and Topologic Gumblar Dragon (also Forbidden, see above) by banishing defunct Warriors from the GY. Too consistent with Isolde, Two Tales of the Noble Knights. This card also played a key role in Diamond Dude Turbo decks by banishing warriors from your GY so you could revive them with Dimension Fusion (Above). This card is Unlimited in the TCG.
Giant Trunade	Clears back field and prepares for OTK. Harder to stop than Heavy Storm (Which is also Forbidden) because it doesn't destroy. Mainly banned for it being able to recycle and reuse Spell/Trap Cards with effects that can only be used a limited amount of times while they are on the field. It's notable that effects that consistently bounce your own Spell/Traps are very rare due to this. Hey, Trunade! was designed to be a fair version of this card.
Graceful Charity	Too fast. You draw before you discard. Sets up Graveyard. Although it seems like an even trade, it can be better than Pot of Greed in more Graveyard-reliant Decks.
Harpie's Feather Duster	Too powerful. Clears out the opponent's back row while yours is safe. Can be searched by Hysteric Sign. This card is Limited in the OCG.
Heavy Storm	This on first turn is usually catastrophic for the opponent, and not everyone manages to set Starlight Road or THRIO on their first turn. Can even benefit you by clearing up useless space or destroying your own Pendulum Scales so you can trigger their effects, activate more, then Pendulum Summon them back for OTK's, though Master Rule 4 makes this far trickier to pull off now.
Kaiser Colosseum	Powerful and splashable floodgate that prevents your opponent from Summoning more monsters than you control. Unlike other common floodgate cards, it does not have to be set before activation, and only directly affects your opponent. Can stop the opponent from being able to play at all if you have just 1 very powerful boss monster like Master Peace, the True Dracoslaying King or Majespecter Unicorn - Kirin (both Forbidden; see above). This card is Unlimited in the OCG.
Last Will	Universal searcher. Mainly was Forbidden for making the extremely fast Catapult Turtle FTK and searching Sangan for Chaos Emperor Dragon - Envoy of the End; however, Catapult Turtle's errata now makes its effect Limited to once per turn, and both Sangan and Chaos Emperor Dragon have been errata'd. Can also potentially create FTK's by summoning Cannon Soldier from your deck (in the TCG). After activation, its effect can be used any time that turn, even during the Battle Phase.
Mass Driver	Abused in many Decks to form a FTK, since it does not use up the Normal Summon and can be used multiple times a turn. Finishing move.
Metamorphosis	Was a key part of the Goat Control Deck and has too many good combos. Notable ones include Beast King Barbaros → Cyber Twin Dragon or Blaze Fenix, the Burning Bombardment Bird and Metal Reflect Slime/Tragoedia/REDMD → Cyber End Dragon, Destiny End Dragoon, Gaia Drake, the Universal Force or Naturia Exterio. With the introduction of more Level-manipulation cards and easier Summoning, this card is much less likely to come back.
Mirage of Nightmare	Too fast. If it gets destroyed, you don't need to discard, so it can be as good as, if not better than, Pot of Greed. Also combos with Emergency Provisions, Solomon's Lawbook, Gravelstorm, and MST extremely well. Its discarding effect Devastating in Dark World, Burning Abyss, and Fabled Decks.
Painful Choice	Gets a good card or sends cards that work well in the Graveyard; similar to activating 4 Foolish Burials at once. Instant Graveyard setup for Decks like Plants, Infernity, Dragon Rulers, Zombies, and Chaos Dragons to name a few. With more and more cards that gain advantage when sent to the Graveyard, this card becomes even more powerful.
Pot of Greed	Instantly gives +1 in card advantage to the user for absolutely no cost. Too easy to use (literally every Deck in the game would be improved by adding this card to it). Forcing all competent Decks to run this card to avoid being at a disadvantage would be unfair. Fairer versions of this card are constantly being made to this day.
Premature Burial	Fast revival. Formerly looped with Brionac, Dragon of the Ice Barrier (though Brionac has now been errata'd so it can't bounce your own cards) and Giant Trunade, which is also Forbidden. There are also combos that allow 1 Special Summon per turn through cards like Dewloren, Tiger King of the Ice Barrier, Falcon of Mist Valley, etc. Searchable and reusable via Hidden Armory. Overdone Burial was designed to be a fair version of this card.
Rank-Up-Magic Argent Chaos Force	Can be sent to the Graveyard by Foolish Burial Goods, Beatrice, Lady of the Eternal or Curious, the Lightsworn Dominion, from where it can be added to the hand via its own effect, such as when you Xyz summon Number 39: Utopia Beyond, which can make the ATK of all of your opponent's monsters 0. This allows for the easy searching of a Rank-Up-Magic card to summon Number S0: Utopic ZEXAL for a lockdown. This card is Unlimited in the OCG.
Sky Striker Mobilize - Engage!	Free +1 with 1 of the 2 gained being a free search. A better Pot of Greed in Sky Striker Decks. This card is Semi-Limited in the OCG.
Snatch Steal	Gives near permanent control. Opponent's LP gain can be avoided entirely by either stealing a strong monster and consistently attacking, or using it as a Fusion/Synchro/Xyz/Link material for a Summon. Searchable and reusable via Hidden Armory. Almost as, if not more powerful than, Change of Heart (see above).
Soul Charge	Incredibly powerful Spell card that revives up to five monsters from your Graveyard for easy Synchro/Xyz/Link Summons in almost every Deck. While it forces you to skip your Battle Phase that turn and has an LP loss correlative to the number of revived monsters (if you're reviving fewer monsters, you lose less LP, if you're reviving more monsters, you lose more LP (though this can be overridden if played alongside other cards)), these restrictions are usually offset by the very large field advantage offered by it.
Spellbook of Judgment	One of the most broken Spell Cards ever made. An incredible searcher for Prophecy Decks, adds several Spellbook Spell cards from your Deck to your hand during the End Phase of the turn that it's activated, like Secrets, Master, Power, Fate, Wisdom, Life, Eternity, Star Hall, and Tower for every Spell card played. Last effect Summons great Spellcasters depending on the number searched such as Jowgen the Spiritualist (seals Special Summons), Kycoo the Ghost Destroyer (prevents Banishing), Maiden with Eyes of Blue (stuns opponent), Justice of Prophecy (who then searches another Spellbook and High Priestess of Prophecy), Dark Magician of Chaos (who can then retrieve any Spell), and even World of Prophecy (can act like a nuke). Can be searched easily itself with Secrets, Master (Copying Secrets), Spellbook Magician of Prophecy, Spellbook Library of the Crescent, and Justice of Prophecy. Can be reused with Tower, Magician of Faith, DMoC, Eternity (after banished with Spellbook of Fate or High Priestess of Prophecy), or Master (copying Eternity).
That Grass Looks Greener	Powerful, costless Graveyard setup card that instantly sends cards from your Deck to the Graveyard until you have the same number of cards in your Deck as your opponent. Similar to Monster Gate and Reasoning (both Limited), but can be better since there is more control over the number of milled cards. Mainly hit due to abuse in 60-card Decks that focus heavily on Infernoids, Paleozoics, and Fairy Tail - Snow (Also banned in the TCG, See above) since it can instantly send 20 cards from your Deck to your Graveyard against most other Decks that run only 40 cards. Can be searched by Left Arm Offering. This card is Unlimited in the OCG.
The Forceful Sentry	A Confiscation (above) with no cost. Returns the card to the Deck rather than discarding it to the Graveyard. Having a card in the Graveyard is usually considered to be better that having it in the Deck. The Humble Sentry was intended to be a fair(ly bad) version of this card.
Last Turn	Turns around the game with little to no effort. Overwhelmingly flexible with various Decks and monsters. An instant win is guaranteed when you control a monster that prevents your opponent from Special Summoning OR can create an instant Draw. Easy to get down to 1000 or less LP with cards like Wall of Revealing Light, Inspection, and Backs to the Wall.
Life Equalizer	This card forms OTKs with cards such as Magical Explosion and Blasting the Ruins, and its steep requirement can easily be met with cards such as Chicken Game (Forbidden in the TCG), Upstart Goblin, and Wall of Revealing Light(Limited in the TCG) by drawing out your Deck with Royal Magical Library. This card is Unlimited in the TCG.
Magical Explosion	Even at 1, Magical Explosion FTK has a very high success rate as the game progresses. This card is Limited in the TCG.
Return from the Different Dimension	Similar to Dimension Fusion (above). Creates very easy OTKs, especially in Dragon Ruler Decks. Easy to prevent the monsters from being banished again since you can just Synchro, Xyz, or Link Summon with them.
Royal Oppression	One card to continuously stop a large number of cards and cripple a large number of Decks with a fairly low cost. Some Decks abuse the fact that it cannot be used in the Damage Step. Can stop a larger variety of cards than Solemn Warning, which has a larger cost and can only be used once. Used in swarm Decks, where you would swarm with a lot of big monsters, and then flip this over.
Self-Destruct Button	Mainly Forbidden for causing too many draws in Tournaments and messing up Ranked Games. This card is Unlimited in the OCG.
Sixth Sense	Potentially one of the strongest forms of draw power, being able to draw up to 6 cards from one effect. The drawback is also potentially beneficial, especially with more Graveyard-reliant Decks. The drawing aspect can be rigged with That Six.
Time Seal	Forces the opponent to skip a Draw Phase, which is lethal when they are topdecking. Unlike Drastic Drop Off, this card can be chained anytime, making it much better; also with Mask of Darkness and Tsukuyomi at 3, lockdown Decks could take unfair advantage.
Trap Dustshoot	Devastating to the opponent if played on them during their first turn. Broken when combined with other Traps like Mind Crush. If used early on, it creates a situation where your opponent will have a lot of trouble recovering. Many thought that the opponent having to have at least 4 cards in their hand was too fair a restriction to ban it. But, it is horrible to go against Turn 1.
Ultimate Offering	A cheap way to swarm the field, resulting in easy Xyz/Link Summons. Gadgets can spawn Rank 4's like mad (as well as Rank 5 with Gear Gigant X and Jumbo Drill around). The effect used to be that both players could use the effect, but it was errata'd so only the controller of the card can use it, which gives a huge advantage. Also abusable in various other Decks such as Madolche, Blackwing (when comboed with Black Whirlwind), and Empty Jar.
Vanity's Emptiness	One card that can continuously stop a large number of cards and cripple a large number of Decks with no cost. While it's easily destroyed when another card is sent from your Deck or field to your Graveyard, this can sometimes work in the user's favor when something deliberately sends a card to your Graveyard (e.g. activating Mystical Space Typhoon on an opponent's card, or a search card like Reinforcement of the Army) so you can keep Special Summoning on your turn. Pendulum Decks also circumvent its downside by going from the field to your Extra Deck instead, opening it up to further abuse. This card is Limited in the OCG.
Limited
Altergeist Multifaker	Key card of Altergeist Decks, allows for amazing versatility in getting the Altergeist you need, and sets up the Summon of Altergeist Hexstia. Combos unfairly with Altergeist Silquitous and Personal Spoofing.
Armageddon Knight	Sends ANY Dark monster from your Deck to the Graveyard whenever it's Summoned. Can lead to crazy power-plays just by simply dumping one certain monster and can trigger monster effects like Archfiend Heiress, Elemental HERO Shadow Mist and all the Shaddoll monsters. Can be searched by Reinforcement of the Army, Mystic Tomato, and Summoner Monk.
Beatrice, Lady of the Eternal	Very good Rank 6 Xyz Monster with a fantastic effect. Can easily be Xyz Summoned in Burning Abyss decks by using Dante, Traveler of the Burning Abyss (Limited in the OCG) as Xyz material (albeit with the downside of its Quick Effect not being usable that turn), and can send any card from your Deck to the Graveyard during either player's turn, allowing you to search out Limited cards like Graff or Cir, or interrupt your opponent's plays by sending Farfa, Alich, or Mischief of the Gnomes from your Deck to the Graveyard. It can also replace itself with Dante, Pilgrim of the Burning Abyss when it dies. Even more abusable in non-Burning Abyss decks since its Quick Effect can be used right away, and even chained to cards like Bottomless Trap Hole, Compulsory Evacuation Device, and Torrential Tribute. This card is Unlimited in the OCG.
Black Dragon Collapserpent	Can special summon itself from the hand by banishing any LIGHT monster from your graveyard, working well with cards such as Eclipse Wyvern (Forbidden in the TCG) and Thunder Dragons, and can also search White Dragon Wyverburster (also Limited in the TCG, see below) when it's sent from the Field to the Graveyard, mostly for Link Summons of Guardragon monsters. This card is Unlimited in the OCG.
Blaze Fenix, the Burning Bombardment Bird	Very powerful Fusion Monster with a deadly burn effect. Creates easy OTK's/FTK's when used in conjuncture with cards like Ancient Fairy Dragon, Black Garden, and Fusion Gate, or with Elemental HERO Electrum, Fusion Gate and Chain Material. This card is Unlimited in the TCG.
Chronograph Sorcerer	Allows for free Pendulum spamming from the hand while keeping your Pendulum Summon in reserve. Combos with Heavymetalfoes Electrumite (see below). Probably hit due to many of the overpowered Pendulum Monsters being Limited in the OCG rather than Forbidden. This card is Unlimited in the TCG.
Cir, Malebranche of the Burning Abyss	Key card in Burning Abyss. Can Special Summon any Burning Abyss monster from your Graveyard whenever it's sent to the Graveyard, allowing easy recovery, or to Summon another Dante, Traveler of the Burning Abyss, Virgil, Rock Star of the Burning Abyss, or get setup for Fire Lake of the Burning Abyss again mid to late-game. Can be searched by Tour Guide from the Underworld and Graff, Malebranche of the Burning Abyss (both Limited in the TCG). This card is Unlimited in the OCG.
Crystron Halqifibrax	Free Tuner monster Summon without restricting you to Synchro Summons, thus opening up various overpowered Link Summon combos. Can go into a free T.G. Wonder Magician or Formula Synchron as a Quick effect, gaining large advantage in the process. Is the single reason why some Tuners are on the OCG Forbidden/Limited list at all. This card does not exist yet in the TCG.
Cyber-Stein	Can lead to easy OTKs with Fusions like Blue-Eyes Ultimate Dragon, Cyber End Dragon, or Cyber Twin Dragon equipped with Megamorph, or can lead to an instant lockdown with Naturia Exterio or The Last Warrior from Another Planet. Cost is high, but can be circumvented if combined with DNA Surgery (calling Psychic-type) and Brain Research Lab or Telekinetic Charging Cell and if the effect goes through, it's devastating. Can be searched easily by Gear Gigant X. This card is Unlimited in the OCG.
Daigusto Emeral	First effect enables easy recursion for any deck and can generate loops at multiple copies, especially in Zoodiac decks. Second effect can revive strong beaters or combo pieces, such as Gaia Saber, the Lightning Shadow, Harpie Lady, and Metalfoes Crimsonite. This card is Unlimited in the OCG.
Danger! Nessie!	Important monster in the Danger! engine. Can potentially special summon itself from the hand and draw 1 card with its own effect, while it can also add a Danger! monster from the deck to the hand. Considered more crucial to the deck than Jackalope and Tsuchinoko, so it got hit further to 1. This card does not yet exist in the OCG.
Dark Grepher	After Armageddon Knight was Limited, this card took over its role in kick-staring unfair Link combos. Searchable by Isolde, Two Tales of the Noble Knights. Hit to ensure said combos could never be viable again. This card is Semi-Limited in the OCG.
Dewloren, Tiger King of the Ice Barrier	Creates loops and OTKs when used with cards like Grandsoil the Elemental Lord (now errata'd to once per turn; see below), Symbols of Duty, or Symbol of Heritage (Limited). Used to be Summoned easily using Elder Entity Norden (Also Forbidden), as Synchro Material. Can also reuse cards like Call of the Haunted, Fiendish Chain, Abyss-sphere, etc.
Dinomight Knight, the True Dracofighter	Allows easy searching and/or activation of True Draco and True King Continuous Traps directly from your deck, without needing to be set first, all of which allow the player to Tribute Summon another "True Draco" during the opponent's turn on top of their other powerful effects. Because this effect is not a hard once-per turn, this means that multiple "Dinomight" can activate their effects in 1 turn. This card is Unlimited in the OCG.
Dinowrestler Pankratops	Strong beater that can special summon itself whenever your opponent has more monsters than you do, and can tribute any Dinowrestler monster on your field (even itself) to destroy 1 card on the field during either player's turn, making it a good disruption card on your opponent's turn. Essentially a better Cyber Dragon. This card is Semi-Limited in the OCG.
Evigishki Gustkraken	Awesome Hand control card. There is a loop where this card is used within a Gishki-Hieratic hybrid Deck and can be bounced repeatedly with Constellar Ptolemy M7 to shut down the opponent's hand. It didn't help that Hieratics Summon Level 6 monsters with the greatest of ease. This card is Unlimited in the OCG.
Evigishki Mind Augus	Can greatly hinder opponent's Graveyard while recycling yours, letting you reuse your Gishki monsters/Spell cards. Key card of the Gishki FTK. This card is Unlimited in the OCG.
Exodia the Forbidden One	Instant win card. These cards are more likely Limited for lore reasons, as it is stated in the anime that only 1 real copy of each card exists (though several fakes have been made). Adding more than one of each card to an Exodia deck would probably make it function less consistently due to dead drawing multiple copies of the same card.
Left Arm of the Forbidden One
Left Leg of the Forbidden One
Right Arm of the Forbidden One
Right Leg of the Forbidden One
Gem-Knight Master Diamond	Can copy the effects of other Gem-Knight monsters, most importantly Gem-Knight Lady Lapis Lazuli to create a burn FTK. After the release of Gem-Knight Phantom Quartz, an FTK combo could be started with just Brilliant Fusion and any Gem-Knight Monster in the starting hand. This card is Unlimited in the OCG.
Genex Ally Birdman	A universal tuner that can be Special Summoned easily. Creates loops and even OTKs generating lots of monsters in Karakuris, Agents, Hieratics, and other Decks if used right. Combos very well with Divine Wind of Mist Valley (which is also Limited). Also part of the Gallis OTK and Divine Wind FTK.
Graff, Malebranche of the Burning Abyss	Can Special Summon any Burning Abyss monster from your Deck whenever it's sent to the Graveyard, allowing you to Xyz Summon another Dante, Traveler of the Burning Abyss, Synchro Summon Virgil, Rock Star of the Burning Abyss, or setup for Fire Lake of the Burning Abyss. Can be searched by Tour Guide from the Underworld (also Limited in the TCG; see below) and reused by Cir, Malebranche of the Burning Abyss (also Limited in the TCG) or Dante. This card is Unlimited in the OCG.
Harmonizing Magician	A Tuner Pendulum Monster that Special Summons from the Deck any Magician when Pendulum Summoned. Has serious downsides, however. Like Chronograph Sorcerer (above), likely hit due to powerful Pendulum Monsters in the OCG being Limited rather than Forbidden. This card is Unlimited in the TCG.
Ignister Prominence, the Blasting Dracoslayer	This card can eliminate an opposing card for free thanks to its second effect while getting around cards that are immune to targeting and/or destruction. Its second effect also fuels the Summon of Dinoster Power, the Mighty Dracoslayer and Majester Paladin, the Ascending Dracoslayer, which can lead to more branching plays. This card is Unlimited in the OCG.
Infernity Archfiend	Key card in Infernity Decks. Can be Special Summoned easily through its own effect or cards such as Stygian Street Patrol and Summoner Monk. Searches any Infernity card from your Deck when Special Summoned, as long as you have no cards in your hand. No once per turn restriction allows it to create OTK's and net multiple searches if you're good enough. This card is Unlimited in the OCG.
Lonefire Blossom	Search and Special Summon ANY plant; this includes Sylvans, Tuners, Dandylion, Mystic Tomato, Tytannial, Princess of Camellias, Gigaplant, etc. This card is Unlimited in the TCG.
Luster Pendulum, the Dracoslayer	Key card in the Dracoslayer engine. Can destroy any other Pendulum Scale you have and search another copy of that Scale, providing you with more resources. Can trigger the effects of cards such as Performage Plushfire (Forbidden) or Guiding Ariadne. Can be searched easily itself with Draco Face-Off, Ignister Prominence, the Blasting Dracoslayer (Limited in the TCG), or Majester Paladin, the Ascending Dracoslayer. This card is Unlimited in the TCG.
Morphing Jar	High draw power. Messes up opponent's hand. Sets up Graveyard. However, the opponent can also abuse this. Has its own OTK/FTK Deck. Can also cause an OTK/FTK with Jackpot 7.
Necroface	Banish Decks of any sort LOVE this card. Has the potential of being a powerful beater and resets and/or sets up Banished cards. Abusable with Gold Sarcophagus, Allure of Darkness, and Pot of Desires. Combined with Soul Absorption is a free 5500 Life Points gained when banished. Having multiple copies can loop them, chain their own effects when banished from the Deck (especially with Pot of Acquisitiveness), or make OTKs (Necro mill OTK). Combos EXTREMELY well with Inferno Tempest, Shiranuis, and PSY-Framelord Omega (below). This card is Semi-Limited in the TCG.
Nekroz of Unicore	Key card in Nekroz. Can negate the effects of any monster Special Summoned from the Extra Deck, and can recycle any Nekroz card from the Graveyard. Combos extremely well with Nekroz Kaleidoscope to send Herald of the Arc Light from your Extra Deck to the Graveyard to search out any Ritual Monster or Ritual Spell card from your Deck. This card is Semi-Limited in the OCG.
Night Assailant	Must be at 1 otherwise this card will just recycle the other one when discarded and an infinite loop will be created making +0 discards, which would lead to cards like Snipe Hunter wiping out your whole field or Dark Crusader having Unlimited attack points, etc.
Phantom Skyblaster	Summons tokens to your field up to the number of monsters you control (including itself) when Normal/Flip Summoned, allowing for easy Link Summons. Can also inflict 300 points of damage to your opponent for each Skyblaster monster you control once per turn, useful when going into time. This card is Unlimited in the OCG.
PSY-Framelord Omega	Amazing Level 8 Synchro Monster that can banish itself and a card in the opponent's hand during either player's Main Phase, return a banished card to the Graveyard during the opponent's Standby Phase, and can even recycle itself and one other card in either player's Graveyard during your Main Phase. Mainly hit due to a hand loop in the OCG involving Synchro Summoning 3 copies of this card in one turn to banish 3 cards in your opponent's hand and the release of Junk Speeder allowed it to do the same in the TCG. Abusable in other Decks like Zombies, Infernoids, and ABCs. Its ability to remove itself from the field also makes it potent under Master Rule 4.
Ritual Beast Ulti-Cannahawk	Key Fusion Monster in Ritual Beast Decks. Can search any Ritual Beast card. Generates huge card advantage by repeatedly fusing and de-fusing to use its effect multiple times. At 1, it's much easier to permanently eliminate this card. Additionally, it effectively prevents Spiritual Beast Rampengu from searching out Spiritual Beast Cannahawk, another key searcher. This card is Unlimited in the OCG.
Salamangreat Gazelle	Key card in the Salamangreat archetype. Special summons itself whenever a Salamagreat card (except another Gazelle) is sent to the graveyard, and can then send any Salamangreat card (except another Gazelle) from your deck to the graveyard, normally either Salamangreat Spinny to extend or Salamangreat Roar to be recovered with Salamangreat Sunlight Wolf, which then recovers the Gazelle, starting off near-endless recursion power.
Saryuja Skull Dread	Allows you to draw 4 cards and then put 3 on the bottom of your deck when it is Link Summoned using 4 monsters with different names, giving you significant control over what you want in your hand, and can also special summon any monster from your hand when Link Summoned using 3 or more monsters with different names. Hit due to abuse in Guardragons in the OCG. This card is Unlimited in the TCG.
Servant of Endymion	Key monster in the Endymion Archetype. Can special summon any monster with 1000 or more ATK from your deck that you can place a Spell Counter on, and it can also gain spell counters whenever a spell card is activated, or during your opponent's turn by discarding one card, it can place 1 spell counter on every card on your field that can have one. Was a key card in the Tempest Magician FTK (though Tempest Magician is now Forbidden). This card is Unlimited in the OCG.
Sky Striker Ace - Kagari	Key monster and main attacker in Sky Striker decks. Allows recursion and abuse of Sky Striker Mobilize - Engage!(Semi-Limited in the OCG). This card is Unlimited in the TCG.
Souleating Oviraptor	Searches or mills any Dinosaur of your choice, and can revive any Dinosaur by destroying another; if destroying Babycerasaurus (Limited in the OCG) or Petiteranodon, this can generate even more advantage for Synchro, Xyz, and/or Link Summons. This card is Unlimited in the TCG.
Speedroid Terrortop	Can Special Summon itself when you have no monsters, then search Speedroid Taketomborg, which also Special Summons itself, letting you make a Rank 3 Xyz Monster with one card without using your Normal Summon. Common choices include M-X-Saber Invoker (see above) and Dante, Traveler of the Burning Abyss to kick-start combos, and Totem Bird for disruption. Can also search other Speedroid monsters, such as Red-Eyed Dice, which can be used for Synchro plays.
SPYRAL GEAR - Drone	Key card in SPYRALs. Rearranges the top 3 cards of the opponent's deck upon being summoned, eliminating any guesswork on the player's part for big plays while also potentially interrupting your opponent's next few draws, unless your opponent plays a Searcher immediately afterwards. Can tribute itself to permanently boost the ATK of a SPYRAL by 500 for each card your opponent controls, and can even chain itself to cards like Compulsory Evacuation Device and Torrential Tribute. Lastly, it can banish itself and another SPYRAL card from your Graveyard to retrieve SPYRAL Super Agent, preparing setup for future plays. This card is Unlimited in the OCG.
SPYRAL Quik-Fix	When combined with SPYRAL Double Helix, Inferno Reckless Summon, and especially Machine Duplication, this card is able to create some insane combos and loops. At 1, it's much easier to permanently eliminate this card. Additionally, it effectively prevents circumvention of its self banishment effect after revival, as the only other archetype member eligible to use alongside it as Xyz Material is SPYRAL GEAR - Drone(see above). This card is Semi-Limited in the OCG.
Supreme King Dragon Darkwurm	Free monster that also searches a generic Scale 0 when sent to GY by Dragon Shrine or Dragon Ravine. This card is Unlimited in the TCG.
Tempest, Dragon Ruler of Storms	One of the four "Adult" Dragon Ruler monsters (see above), can easily special summon itself from the hand or grave by banishing 2 WIND and/or Dragon-type monsters from your hand or grave, and can be searched easily with cards like Lightning, Dragon Ruler of Drafts, Dragon Ravine, Dragon Shrine, Gold Sarcophagus (also Limited, see below), etc. However, the other 3 "Adult" Rulers (Blaster, Redox, and Tidal) are still forbidden, making this less powerful on its own.
Thunder Dragonhawk	Can revive any of your Thunder Dragon monsters that is banished or in your graveyard by discarding itself, and can also patch up bad hands when it is sent from the field to the graveyard or banished, by shuffling and redrawing any number of cards you hold. This+Batteryman Solar=3 Thunder Dragon Colossus (See above) or Saryuja Skull Dread+Thunder Dragonduo. This card is Unlimited in the TCG.
True King Lithosagym, the Disaster	Can generate excellent advantage due to its interactions with other cards. By destroying cards like "Babycerasaurus", "Baobaboon", "Petiteranodon" and other "True Kings", the cost of Summoning this card is effectively nullified. True King of All Calamities can even go a step further by making that cost an efficient nuking tactic in an open game state. Additionally, it can banish three cards from the opponent's Extra Deck of your choice, which is not only rare among others like it, but devastating for Link Summoning Decks. It also revives a non-EARTH Wyrm when destroyed by a card effect, which is easy to trigger. This card is Unlimited in the OCG.
White Dragon Wyverburster	Can special summon itself from the hand by banishing any DARK monster from your graveyard. Can work well with Thunder Dragons and some other DARK monsters, and can also search Black Dragon Collapserpent (also Limited in the TCG, see above) when it's sent from the field to the graveyard, mostly for Link Summons of Guardragon monsters.
Zoodiac Ratpier	Instant +1. When attached to a "Zoodiac" Xyz Monster, that monster can Special Summon another copy of this card by detaching a material. As it is not once per turn, it can be re-used by Summoning another Zoodiac Xyz Monster on top of the old one, re-attached with "Zoodiac Tigermortar" and recycled with "Zoodiac Combo". When two others are Summoned by its effect, it allows for easy Rank 4 Xyz Summons, such as "Brotherhood of the Fire Fist - Tiger King", "Daigusto Emeral" or "Bujintei Kagutsuchi", while the original usually ends up as "Zoodiac Drident" (Forbidden). Can be searched by "M-X-Saber Invoker", "Zoodiac Broadbull" (Forbidden), "Fire Formation - Tenki" or "Zoodiac Barrage" (Forbidden in the OCG).
A Hero Lives	Generates OTKs. Can be used with Elemental HERO Stratos(see above), who then searches for Elemental HERO Bubbleman, to swarm the field without using the Normal Summon. The steep cost, on the other hand, restricts early playability. This card is Semi-Limited in the OCG.
Card Destruction	Sets up your Hand and possibly Graveyard. Can mess up, or help with, the opponent's Hand, but can also set up their Graveyard. Works very well with Dark World and Fabled. Like Morphing Jar, can be more devastating to your opponent and more beneficial to you.
Card of Demise	Lets you draw until you have 3 cards in your hand. While you can't Special Summon or inflict damage for the rest of the turn it's used, you can set a lot of Traps or activate Pendulum Scales, making it useful in stun Decks that use a lot of backrow. The latter drawback can also be circumvented by inflicting as much damage as possible before activating it in your Main Phase 2. This card is Unlimited in the OCG.
Chain Strike	Inflicts massive damage if used right. Key card of Chain Burn Decks such as Chain Strike OTK. This card is Unlimited in the OCG.
Dimensional Fissure	Good counter to Graveyard-reliant Decks like Dark World. Similar to Macro Cosmos, which is also Limited. Some Decks abuse the mechanics of this card. This card is Unlimited in the OCG.
Divine Wind of Mist Valley	Special Summons any Level 4 or lower WIND monster from your Deck if a WIND monster returns to the hand. Creates loops at more than 1 when combo'ed with Ancient Fairy Dragon (see above). Works well with Genex Ally Birdman (Limited) and Harpie Dancer. Can be searched easily with Terraforming (Semi-Limited in the TCG, Limited in the OCG). Key card of the Divine Wind FTK.
Draconnection	Adds any dragon-type monster from your deck to your hand at the cost of shuffling one from your hand into your deck with the same level as the searched monster. A great search card for dragon decks, hit to slow down Guardragons, which were topping in the OCG. This card is Unlimited in the TCG.
Dragonic Diagram	A strong Field Spell Card that can search any True Draco or True King card from your Deck to your hand by destroying any other card you control or in your hand, and can also give all True Draco and True King monsters 300 ATK and DEF while protecting those that are Tribute Summoned from being destroyed by battle once per turn. The destruction effect is not a cost, and can thus trigger the effects of the True Kings and many other archetypes like Dinosaurs. Can be searched by Terraforming and Metaverse (both Limited, see below).
Draco Face-Off	A versatile card that easily sets up a Dracoslayer Pendulum Scale OR Special Summon a Level 4 Dracoslayer monster for further plays while setting up Pendulum Summons. It can easily tutor Luster Pendulum, the Dracoslayer, which further aids Pendulum Summons while triggering the effects of monsters such as Guiding Ariadne. Since it is a Quick-Play Spell, it can also steal wins during the Battle Phase. This card is Unlimited in the OCG.
Emergency Teleport	A versatile search card that Summons Level 3 or lower Psychic-Type Monsters for easy Synchro Summons, Low-Level Kozmo monsters which can then banish themselves on the fly to Summon stronger ones from your hand, and Super Quantum Blue Layer for both pure and hybrid Super Quant Monarch Decks, which were topping in the OCG. This card is Semi-Limited in the OCG.
Final Countdown	Powerful alternate win-condition Spell card. Instantly wins the Duel in 20 turns (or 10 of your turns) if you can stall your opponent long enough with cards like Waboku, Threatening Roar, Battle Fader, Swift Scarecrow, Frozen Soul, Thunder of Ruler or One Day of Peace (which is also Limited). Gold Sarcophagus can get this card to your hand easier. This card is Unlimited in the OCG.
Foolish Burial	Many Decks rely on the Graveyard a lot. Works well with cards like Wulf, Lightsworn Beast, Plaguespreader Zombie, etc.
Gateway of the Six	Can gain counters whenever a Six Samurai monster is Normal or Special Summoned. With the introduction of Legendary Six Samurai monsters that can Special Summon themselves, and the ability for Gateway to remove Bushido Counters from anywhere on your side of the field, 2 or more of these would result in constant searching of Six Samurai monsters for every Summon. Can create ridiculous swarming, loops, lockdowns, and even FTKs if you control other cards that gain Bushido counters on the field. In short: You use this, you then do literally whatever you want. However, Six Samurai's haven't been relevant in a long time, so it came back to 1. This card is Unlimited in the OCG.
Gold Sarcophagus	Went on and off the banlist many times in the past, formerly for being able to add any card from your Deck to your hand, but it takes 2 turns before the card gets to your hand, which is rather slow nowadays. Now, it was hit due to being similar to Foolish Burial (also limited, see above), but for triggering the effects of banished monsters, such as Necroface (Also Limited in the OCG, see above), Dragon Rulers (now Forbidden, sans Tempest), Shiranui, Metaphys and Thunder Dragons.
Infernity Launcher	Easily searched by Infernity Archfiend(Limited in the TCG). Creates loops at more than 1. First effect allows you to empty your hand to prepare for its second effect.
Into The Void	Lets you draw 1 card from your deck with the only downside being that you have to have 3 or more cards in your hand to activate it. The downside of discarding your hand during the End Phase can be circumvented with cards that work well upon being discarded, or by using it in deep draw FTK's so you win before the downside kicks in. This card is Unlimited in the OCG.
Magical Mid-Breaker Field	Used in many Extra Link Decks to protect their field. This card is Unlimited in the OCG.
Mask Change II	This card allows the player to Summon powerful Masked HERO Fusions such as Masked HERO Dark Law or Masked HERO Acid using non-HERO monsters, and its drawback is easily circumvented by using Burning Abyss monsters. This card is Unlimited in the TCG.
Mind Control	Unlike Change of Heart, you can't attack with or Tribute the monster, but you can still use its effects and it still can be removed via a Fusion/Synchro/Xyz/Link Summon. This card is Semi-Limited in the TCG.
Monster Reborn	One of the most powerful Spell Cards in the game. Almost as easy to use as Pot of Greed. Can be a very powerful topdeck with very little setup. Can even Special Summon from the opponent's Graveyard, further punishing them if you manage to destroy a strong monster they control.
Mystic Mine	Prevents the player who controls more monsters than their opponent from attacking or activating any monster effects, but it destroys itself during the End Phase if both players have the same number of monsters on their fields. Combos very well with Metaverse (Limited). Can shut down entire decks by itself and can sometimes force a win by deck-out there if the opponent has a monster-heavy deck with next to no S/T removal Spell/Trap cards like Cosmic Cyclone and Twin Twisters, or fodder generators like Ojama Trio and Black Garden. This card is Unlimited in the TCG.
One Day of Peace	Easily the best stall card in the game. The +1 for your opponent is offset compared to the results. No advantage lost when played. Can be used after you attack to take no damage for a turn. Sets up for big plays and OTKs. Works very well in Exodia/Final Countdown Decks. There is also an OTK/FTK loop with this card in Gishki Decks, where multiple copies of this and other draw cards were repeatedly recycled with Evigishki Mind Augus to Deck out the opponent in a single turn. Can be recycled and reused by Magician of Faith. However, it does give the opponent an opportunity to establish a strong field instead.
One for One	Nice searcher. Formerly abused in Frog Burn FTK, Mind Master OTK, and Plant Synchro. Loss in card advantage is easily recoverable with the right setup. Will probably remain Limited due to Neptabyss, the Atlantean Prince and various combos hinging on other Level 1 monsters such as Level Eater, Jet Synchron, Raidraptor - Last Strix, D/D Lamia and D/D Savant Kepler. This card is Semi-Limited in the OCG.
Pantheism of the Monarchs	A superior Destiny Draw for Monarchs that thins the Deck while drawing out key cards and dumping cards such as The Prime Monarch. The player can also banish this card from the Graveyard afterwards to search another Monarch Spell/Trap card, even another copy of itself at more than 1 and in the same turn it was activated. Can also be searched with Tenacity of the Monarchs. This card also played a key role in Monarch Magical Explosion deep draw FTKs. This card is Unlimited in the OCG.
Pendulum Call	Sets up easy Pendulum Summons with Magician monsters while protecting the player's Pendulum Scales from cards such as Twin Twisters and Wavering Eyes. This card is Unlimited in the TCG.
Pot of Avarice	Recycles the Graveyard while adding draw power. Almost/just as easy to use as Pot of Greed(See below). Excellent in certain Decks, recycling cards like Reborn Tengu, Gadgets, Wind-Ups, etc. Can also put Extra Deck monsters back, leaving you with no Graveyard set-up disadvantage and letting you reuse Limited Extra Deck monsters. Plants abused this card, but the March 2012 lists killed Plant Synchro. Pot of Dichotomy and Jar of Avarice were designed to be fair versions of this card. This card is Unlimited in the OCG.
Primal Seed	Can cause OTK and FTK loops: 2 Primal Seed + Macro Cosmos/Banisher of the Light/Radiance + Anything you want to reuse indefinitely = win For example a FTK would be: On your first turn, you Hand Destruction 1 LIGHT and 1 DARK. Then Special Summon the Envoy. Then Normal Summon Banisher of the Light/Radiance. Now, activate Sparks, activate 1st Primal Seed to get Sparks and 1 of the Banished cards, activate the same Sparks, activate 2nd Primal Seed to get 1st Primal Seed and the same Sparks and repeat for Sparks FTK!!! You can do this with any Effect Damage cards, or ATK boosting cards like Limiter Removal, Rush Recklessly, etc. However, the setup required to enable this FTK loop is far less consistent now when compared to other OTK and FTK loops. This card is Unlimited in the TCG.
Raigeki	Much stronger than Dark Hole (also Limited in the TCG). Destroys only the opponent's monsters. Lightning Vortex was designed to be a fair version of this card. However, monster destruction is less powerful than it once was, so it came back to 1.
Reasoning	Was used a lot by Turbo and OTK Decks. Free Monster or easily dumps other cards to Graveyard, both of which can be beneficial. This card saw heavy play in Infernoids, which can dump vast amounts of Infernoid monsters for future use, causing it to be re-Limited. This card is Unlimited in the OCG.
Reinforcement of the Army	Too broad. This card adds additional speed to many Decks, like Evilswarms, Lightsworns, Six Samurais, tellarknights, HEROs, Ninjas, Inzektors (grabs Dark Grepher or Armageddon Knight), and Infernities (for the same reason as Inzektors). Certain Warrior Decks have their own version of this card, which prevents this from going to 2 to assist other Warrior Decks.
Salamangreat Circle	Can either search any Salamangreat monster from your deck to your hand, or protect a Salamangreat Link monster (that was link summoned using another copy of itself) from other monster effects the turn it's activated. Hit for the same reason as Lady Debug: The deck was too consistent. This card is Semi-Limited in the OCG.
Scapegoat	Summons four tokens that can be used to easily summon various Link Monsters. Was historically Limited due to its stalling power and titular role in Goat Control decks, but got off the list due to the introduction of Piercing effects and the banning of Metamorphosis respectively. This card is Unlimited in the OCG.
Sekka's Light	Allows you to draw 2 cards if you have no Spells or Traps in your graveyard, but you can't activate any other effects for the rest of the duel after using it, except another copy of itself. The downside can be overridden if you establish a strong board of continuous floodgates before activating it, or if you plan an instant win using something like Exodia. This card is Unlimited in the OCG.
Set Rotation	Likely hit due to a loophole involving Field Spells such as "Gateway to Chaos" and "Oracle of Zefra", whose archetype-locked search-on-activation effects are mandatory, therefore preventing their activation in the very likely case the opponent has nothing to search. This means it secures your Field Spell AND locks your opponent's for free, with the only way out for them being using backrow self-removal, which can be a hard hit to recover for some Decks whose Field Spells are vital in getting them going.
Sky Striker Mecha - Hornet Drones	Hit due to its splashability in most Decks alongside Sky Striker Mobilize - Engage! and Sky Striker Ace - Kagari, making this card an easily searchable free Link-2. With Sky Strikers being the main meta Deck at present, this card is more likely to be hit again than unbanned.
Sky Striker Mecha Modules - Multirole	Can send 1 other card you control to the graveyard to prevent your other Sky Striker Spells from being negated that turn, triggering Sky Striker Airspace - Area Zero and clearing unwanted monsters. It can also mass Set several Sky Striker Spells from your Graveyard during your End Phase, giving a free full backrow at the cost of banishing them when they leave the field. Hit to further hurt the deck's insane recursion power. This card is Semi-Limited in the OCG.
Sky Striker Mecha - Widow Anchor	Negates monster effects to stop plays, and steals monsters to stop Summons. Can also enable OTKs. Key card in Sky Striker Decks. This card is Semi-Limited in the OCG.
SPYRAL Resort	Searches any SPYRAL card every turn. Enables OTK if going second. Gives near-blanket targeting protection, useful if going first. Recycles a monster every End Phase. No cost. This card is Semi-Limited in the OCG.
Symbol of Heritage	Can revive any monster if you have 3 or more copies of that monster in your GY. Formerly caused loops with cards like Dewloren, Tiger King of the Ice Barrier (Which is Semi-Limited in the OCG and Limited in the TCG), Ancient Fairy Dragon and Elder Entity Norden (Both Forbidden), and can be reused with cards like Mist Valley Falcon. Searchable by Hidden Armory and Power Tool Dragon. Even easier to abuse in Cyber Dragons, Harpies, and SPYRALs, since they have multiple monsters that treat themselves identically in the GY. Was probably Limited due to most decks in the meta being fast enough now to reach 3 copies effortlessly, or because of Lonefire Blossom coming to 3.
The Beginning of the End	Abused in many DARK decks like Orcust, Phantom Knights', and Danger! decks to get significant draw power, letting you draw 3 cards by banishing 5 DARK monsters from your graveyard while you have 7 or more in your graveyard, and you can also gain the effects of the banished monsters afterwards. Since it is not once per turn, it can be used more than once per turn if you can get enough DARK monsters in your graveyard to use multiple copies of this card. This card is Unlimited in the TCG.
Trickstar Light Stage	Can add any Trickstar monster from your Deck to your hand when activated, and can lock out a Set S/T on your opponent's field until the End Phase whereupon it either forces the activation or sends it to the GY. while also inflicting 200 damage to your opponent each time a Trickstar monster inflicts damage to your opponent: effectively halving the time it'll take to OTK. In effect, this card enables all kinds of 1/2-card combos, ranging from Orcust combos to handloops to repeated searches with Trickstar Candina. This card is Unlimited in the OCG.
Terraforming	Searches any Field Spell. It's especially useful to grab powerful Field Spells early in the game, such as Divine Wind of Mist Valley, Mystic Mine (Limited in the OCG), Dragonic Diagram (Limited), Chicken Game (Forbidden in the TCG), and Union Hangar (Semi-Limited in the OCG); though it can become a dead draw otherwise.
Upstart Goblin	An inferior Pot of Greed that lets you draw 1 card, then has your opponent gain 1000 LP. Previously Limited due to use in Makyura Exodia Decks until Makyura was Forbidden, but later re-Limited again after heavy play in the TCG. 1000 LP is often worth the extra draw power in most decks now anyway. This card is Unlimited in the OCG.
Zoodiac Barrage	Can Special Summon any Zoodiac monster from your Deck by destroying ANY face-up card you control, even itself, Fire Formation - Tenki, or Tensu after they've been used, and can also attach itself to a Zoodiac Xyz Monster if it's destroyed, even by its own effect. Banned due to Zoodiacs creating Tier 0 formats and being an easy Material in general that works well with any card that triggers on being destroyed: they haven't been relevant for quite some time, though, so it came back to 1. This card is Unlimited in the TCG.
Imperial Order	Powerful Spell lock via a Continuous Effect, unlike others that start a chain. This card alone can shut down Decks. However, this card has now been errata'd so that the 700 LP cost occurs during both player's Standby Phases, and it is mandatory, preventing you from turning it off at will during your own Standby Phase.
Macro Cosmos	Same as Dimensional Fissure. Gives an almost automatic win against another player if they run a Graveyard-reliant Deck and you don't. This card is Unlimited in the OCG.
Metaverse	Similar to Terraforming (also Limited, see above), but it can also activate a field spell directly from your deck on your opponent's turn, which can interrupt or shut down plays with Mystic Mine (Semi-Limited in the OCG). Being a Normal Trap also makes it very searchable at more than 1. With this card at 1, it's now much harder to use Mine going first, with the next best options being the more situational Demise of the Land and Pop-Up.
Red Reboot	Shuts down any of your opponent's Trap cards for the duration of the turn it is activated, and can even be activated straight from your hand by paying half your LP. This card is Semi-Limited in the OCG.
Skill Drain	One card to continuously stop a large number of cards. Works well with cards such as Beast King Barbaros and Decks like Qli, Dark World and Yang Zing. See also: Skill Drain Deck. This card is Unlimited in the OCG.
Trickstar Reincarnation	Hit to stop a hand loop which created OTKs. Banishes the opponent's hand instead of discarding, making the retrival of said cards much harder. Insane combo with Droll & Lock Bird. No limit on the number of times you can activate both effects. This card is Unlimited in the TCG.
True King's Return	Easily searched by Dinomight Knight, the True Dracofighter (Limited), and generates easy advantage during either player's turn. This card is Unlimited in the OCG.
Wall of Revealing Light	Facing three in an Exodia Deck with LP recovery would be a real pain, especially because of Hope for Escape. Combos well with Reversal Quiz. Also abusable with Last Turn and Self-Destruct Button, both of which are Forbidden. This card is Unlimited in the OCG.
Semi-Limited
Altergeist Meluseek	Can add any Altergeist monster from your deck to your hand when it is sent to the graveyard, which can work well when used to Link Summon Altergeist Primebanshee, letting you Special Summon Multifaker (Limited) from your deck, and it can then recycle this card or Multifaker when it is sent to the graveyard. This card is Unlimited in the TCG.
Ash Blossom & Joyous Spring	Extremely powerful handtrap, capable of disrupting most combos. No decent deck in the game can play without enabling this card to hit them in some way. This card is Unlimited in the TCG.
Babycerasaurus	Generates excellent advantage when triggered by Dragonic Diagram (Forbidden in the OCG), Lost World, Miscellaneousaurus (Limited in the TCG), Souleating Oviraptor (Limited in the OCG), and "True King Lithosagym, the Disaster" (Forbidden in the TCG). Easily searched by Souleating Oviraptor and Fossil Dig (Semi-Limited in the OCG). This card is Unlimited in the TCG.
Danger!? Jackalope?	Important monsters in the Danger! engine. All of them can potentially special summon themselves from the hand and draw 1 card with their own effects, while they also have good secondary effects when discarded from the hand: Jackalope can special summon a Danger! monster from the deck, and Tsuchinoko can revive itself. These monsters can also enable various deep draw FTKs with the sheer draw power they offer when combined with Allure of Darkness, The Beginning of the End, etc. In other decks they can be used for extra summon/draw power. These cards do not exist in the OCG.
Danger!? Tsuchinoko?
Deep Sea Diva	Good searcher. Creates automatic Level 5-8 Synchros or Rank 2 Xyz when used in conjunction with Abyss-sphere and Atlantean Marksman or Atlantean Heavy Infantry upon Normal Summon.
Galatea, the Orcust Automaton	Allows you to set ANY Orcust Spell/Trap card from your deck, namely Orcustrated Babel (which can make all of your Orcust effects become quick effects), as well as Orcustrated Return (a Destiny Draw for the deck), Orcust Crescendo (can negate almost anything and then search an Orcust monster from your deck, or get back one that is banished), Orcustrated Einsatz (which can set up your graveyard with Orcust Harp Horror for future plays), Orcustrated Core (prevents your Orcust monsters from being destroyed) or Orcustrated Attack or Release, which can stop atacks and Special Summon Link monsters from your Graveyard, respectively. The "cost" to use it's effect recycles Orcust Harp Horror (Forbidden in the TCG) or other Orcust monsters for later use, and if it is extra Linked, it cannot be destroyed by battle.
Lady Debug	Allows you to search any level 3 or lower Cyberse monster from your deck when Summoned. Used as a low-effort combo starter in Salamangreat decks. With Salamangreat Circle, Salamangreat Miragestallio and the then upcoming Cynet Mining, the deck would have had way too many search cards. This card is Unlimited in the TCG.
Mathematician	Splashable Level 3 monster with a good effect. Can send any Level 4 or lower monster from your Deck to the Graveyard when Normal Summoned, and lets you draw a card when it dies in battle. Combos well with Shaddoll monsters or with Felis, Lightsworn Archer to easily Synchro Summon Black Rose Dragon or Arcanite Magician. This card is Unlimited in the TCG.
Performage Damage Juggler	Insanely splashable utility. Key card in Performage Decks. Can negate burn effects or stop OTKs from hand while providing crazy consistency to any Deck running Performages from Graveyard. Mainly hit due to Performage Performapal (PePe) Decks that were topping everywhere. This card is Unlimited in the OCG.
Predaplant Ophrys Scorpio	Can summon Predaplant Darlingtonia Cobra to search cards like Instant Fusion or Brilliant Fusion, before their subsequent use as Fusion/Xyz/Link materials. This card is Unlimited in the TCG.
Thunder Dragonroar	An important monster in the Thunder Dragon Archetype. Can return any of your Thunder Dragon monsters that is banished or in your graveyard to your hand by discarding itself, and can also Special Summon any Thunder Dragon monster from your deck when it is sent from the field to the graveyard or banished. Can easily help to summon Thunder Dragon Colossus (See above), similar to Thunder Dragonhawk (Limited in the OCG, see above). This card is Unlimited in the TCG.
Tour Guide From the Underworld	Good Searcher. Quickly Summons Rank 3 Xyz Monsters by Summoning another copy of itself or another Level 3 fiend-type monster. Good monsters it was used to quickly Summon include Leviair the Sea Dragon, Number 17: Leviathan Dragon, Wind-Up Zenmaines, and Number 30: Acid Golem of Destruction. It saw little use after Sangan, this card's main target, got Forbidden, so it came off the list, but was put back on the list later due to abuse in the Burning Abyss archetype in the TCG, where it can Summon almost any Burning Abyss monster from your Deck to easily make Dante, Traveler of the Burning Abyss.
Trickstar Candina	Searches ANY Trickstar card on Normal Summon, including the infamous Trickstar Reincarnation (see above), recursive with Trickstar Lycoris. Can be searched by Trickstar Light Stage. This card is Unlimited in the TCG.
Allure of Darkness	The most splashable draw card since Pot of Greed. Its "downside" can be used for Graveyard setup. Initially came off the list due to not being as good as it once was, but once Orcust decks started topping in the OCG, it got hit again. This card is Unlimited in the TCG.
Fossil Dig	Searches a large number of Dinosaur monsters, such as "Miscellaneousaurus" for use as a handtrap, "Babycerasaurus"(Limited in the OCG), "Petiteranodon" (both it and "Babycerasaurus" can be destroyed in the hand by the effect of "True King Lithosagym, the Disaster" {Foridden in the TCG} for easy advantage), and "Souleating Oviraptor"(Limited in the OCG), which can search any Dinosaurs this card cannot. This card is Unlimited in the TCG.
Super Polymerization	Powerful, chainable Quick-Play Spell Card that cannot be chained to. Can fuse monsters from either player's side of the field to make Fusion Summons. Mainly abused in HEROes (to Fusion Summon Absolute Zero, Nova Master, Gaia, Great Tornado, The Shining, and Escuridao), Zombies (for Dragonecro Nethersoul Dragon while Zombie World is on the field), and Shaddolls (For El Shaddolls Construct (Forbidden), Winda, Grysta, Shekhinaga, Wendigo, and Anomalilith). Can also be used to fuse any two Synchro or Xyz Monsters from either side of the field to make Elder Entity Norden (Forbidden). Coming back due to Konami's apparent dislike of large combo boards with multiple negates, and this card provides an easy counter to them. This card is Unlimited in the TCG.
Personal Spoofing	Key card of Altergeist Decks, combos insanely with Altergeist Multifaker, allowing for recycling and abuse of that card. Also works well with Altergeist Manifestation, and fairly well with most other Altergeist cards. This card is Unlimited in the TCG.
No longer on list
A-Assault Core	Originally Limited due due to an FTK loop with Firewall Dragon, but came off once Firewall got hit.
ABC-Dragon Buster	Boss "A-to-Z" Monster Summonable if its materials are on the field or in the Graveyard, which is relatively easy to achieve with cards like Ties of the Brethren and Future Fusion. Can banish a card during either player's turn, allowing easy disruption during your opponent's turn and clearing the way for OTK's. It can also escape destruction with its second effect during the opponent's turn, restoring its materials for the next turn to Summon a fresh ABC-Dragon Buster and/or make Rank 4 Xyz Summons. Far outclasses other "A-to-Z" monsters, whose materials must be banished from the field, cannot be Special Summoned from the Graveyard, use Ignition Effects that aren't chainable (excluding A-to-Z-Dragon Buster Cannon), and can only destroy cards (excluding VWXYZ-Dragon Catapult Cannon). However, ABC's aren't relevant anymore, so this came off.
Abyss Soldier	Semi-Limited from April '05 to Sept '05 due to its abuse with Sinister Serpent, allowing free bouncing, once per turn. After Sinister Serpent got Forbidden, this came off the list.
Aleister the Invoker	Easily searched by "Magical Meltdown", and searches "Invocation" upon its Summon, which can Fusion Summon an "Invoked" Fusion Monster by using this card and monsters in either player's Graveyard. When used in combination with the "Windwitch" engine (see "Windwitch - Ice Bell"), this can result in a minimum field of "Crystal Wing Synchro Dragon" and "Invoked Raidjin", and has high versatility given the range of "Invoked" Fusion Monsters.
Apoqliphort Towers	Very powerful boss monster, sporting an immunity to most effects, an effective 3500 attack, and an unstoppable monster-killing effect. Was formerly Forbidden in the TCG, but came off the list due to the introduction of more removal options.
Apprentice Magician	Was used to get Magician of Faith from your Deck face-down to get access to its effect. Nephthys Decks also used it to search Hand of Nephthys to quickly Summon Sacred Phoenix of Nephthys. The Apprentice Magician > Old Vindictive Magician Monarch combo didn't really contribute to its initial Semi-Limitation, so it came off the list. Also, Flip Effect monsters are considered to be too slow nowadays.
Archlord Kristya	Strong ATK, seals Special Summons, and is difficult to get rid of since it goes back to the top of the Deck instead of the Graveyard. Generates a +1 when Special Summoned. Came off due to lack of use in the current meta.
Artifact Moralltach	Can destroy any face-up card your opponent controls without targeting when it's Summoned. Can be searched with Artifact Sanctum and Artifact Ignition. Can be reused with Artifact Failnaught or Call of the Haunted.
Atlantean Dragoons	Amazing Searcher. Adds any Sea Serpent from your Deck to your hand when send to the Graveyard as a cost for a WATER monster's effect. Key card in Mermail Decks. Also allows other Sea Serpents to attack directly, therefore gaining Atlantean Marksman's effect. Can easily be searched with Atlantean Marksman, Genex Undine, and Summoner Monk.
Black Luster Soldier - Envoy of the Beginning	Can be Special Summoned easily, good effects, high ATK. Honest can be used on its first attack, then the 2nd attack would be deadly. Basically a better Chaos Sorcerer (below). See also: Chaos.
Black Rose Dragon	Universal Nuke. See also: Debris-Hime Deck. Top Decks wouldn't really use more than one in their Extra Deck anyways.
Blackwing - Gale the Whirlwind	Can be Special Summoned in Blackwing Decks very easily. A reusable permanent Shrink. Universal Tuner. However, Blackwings haven't done much in a long time, so it was brought down to 3.
Blackwing - Kalut the Moon Shadow	Can easily turn battles around in Blackwing Decks. Unlike Honest, it can even be used when attacking directly for massive damage. However, Blackwings haven't done much in a long time, so it was brought down to 3.
Breaker the Magical Warrior	Back when it was Forbidden/Limited, +1 cards were overpowered; Breaker lets you destroy a card almost for free and you'll still have a monster, or you could leave it as a 1900 Beatstick which was quite a lot at the time.
Brionac, Dragon of the Ice Barrier	Was formerly Forbidden due to a lack of a once per turn restriction, allowing you to bounce cards with its effect multiple times per turn and reuse your own cards for loops and OTK's. Now, it has been errata'd so it can only be used once per turn, and can only bounce your opponent's cards, not your own.
Brotherhood of the Fire Fist - Rooster	Key card in Fire Fists. Adds any Fire Fist monster from your Deck to your hand when Summoned by a Fire Fist monster's effect. Can also search Fire Formation Spell/Trap cards. Can be searched easily with Brotherhood of the Fire Fist - Horse Prince or Fire Formation - Tenki. Can be reused with Brotherhood of the Fire Fist - Spirit or Brotherhood of the Fire Fist - Lion Emperor. Fire Fists aren't relevant anymore though, so it went back to 3.
Brotherhood of the Fire Fist - Spirit	Key card in Fire Fist 3-Axis Deck. Works well with Brotherhood of the Fire Fist - Rooster and Brotherhood of the Fire Fist - Leopard. Searchable via Fire Formation - Tenki and/or Rooster. At 3, easily makes a new Brotherhood of the Fire Fist - Horse Prince every turn. Also reusable via Rekindling and Crane Crane, and can be returned to your hand via Brotherhood of the Fire Fist - Lion Emperor to start the combo all over again. Fire Fists aren't relevant anymore though, so it went back to 3.
Burner, Dragon Ruler of Sparks	Were formerly Forbidden due to being able to easily special Summon their respective Level 7 Dragon Rulers directly from the Deck for easy Rank 7 Xyz Summons and/or Level 8 Synchro Summons. Now that their respective Level 7 counterparts are Forbidden in both the TCG and OCG, these cards came back to 3.
Lightning, Dragon Ruler of Drafts
Reactan, Dragon Ruler of Pebbles
Stream, Dragon Ruler of Droplets
Card Trooper	Can be a good beatstick for 1 turn. Sets up the Graveyard for many Decks. When it dies, you draw a card, so no advantage lost. Combos well with Machine Duplication. However, it's not as good as it once was, so it came off the list.
Chaos Emperor Dragon - Envoy of the End	Was formerly one of the most broken cards in the game, allowing you to nuke both player's fields and hands without destroying, thus getting around cards like Stardust Dragon, Starlight Road or THRIO, and led to the infamous Yata-Garasu Lockdown when combo'd with Sangan (before it was errata'd, see below). Now this card has an errata which makes it a Nomi monster, inflicts damage based on only the opponent's cards sent, not both player's cards, and prevents other card effects from being activated for the rest of the turn, preventing it from comboing with any other cards or effects.
Chaos Sorcerer	Can be Special Summoned easily, decent effect. However, relatively low ATK. With the rise of Chaos Decks, getting this out is even easier than before. Searchable with Justice of Prophecy. Came off the list due to its lack of use in the meta, and Black Luster Soldier - Envoy of the Beginning is considered better anyways.
Chronomaly Nebra Disk	Adds any Chronomaly card from your Deck to your hand other than itself when Normal Summoned, mainly Chronomaly Crystal Skull (who then searches another copy of this card), and Chronomaly Golden Jet, who can be used to make easy Rank 5 Xyz Summons with this card or with Artifact monsters. Has decent ATK. Can also revive itself from the Graveyard for Rank 4 (or 5 with Golden Jet) Xyz Summons if you only control Chronomaly monsters. Mainly hit due to Chronomaly/Artifact builds topping in the OCG before The Duelist Advent.
Coach Soldier Wolfbark	Key card in 4-axis Fire Fist Decks. Special Summons Level 4 Fire Fist or Fire King monsters from your Graveyard for easy Rank 4 Xyz Summons. At 3, can easily make a new Brotherhood of the Fire Fist - Tiger King each turn. Can be searched easily with Fire Formation - Tenki. Came off the TCG list due to the lack of Fire Fist and Fire King Decks topping.
Constellar Ptolemy M7	Good effect. Can be used in Hieratics, Dragunitys, Constellars, or any Deck that makes easy Rank 6 monsters. Automatically usable after one of your other Constellar Xyz Monsters runs out of Materials. Key card for the Evigishki Gustkraken hand loop, which is not relevant anymore.
Cyber Dragon	Can be Special Summoned easily. Good ATK. Usable in many Decks. However, there are increasing numbers of newer monsters with effects similar to this card, and increasing amounts of newer Decks that can Special Summon "a bunch of monsters in one turn", so older Decks need this. Also, the opponent can use Chimeratech Fortress Dragon against you if you're using machines as well (e.g. Morphtronics, Salvo, Gadgets).
Dark Armed Dragon	Can be Special Summoned easily in most DARK Decks. Specific destructive power. High ATK. See DAD Return and Tele-DAD. However, it's not as consistent as it once was, so it came off the list.
D.D. Assailant	Back when this was initially hit, Warrior Toolbox Decks were Tier 1.
D/D Lamia	A reusable Level 1 tuner that can revive itself for Synchro plays by sending any D/D or Dark Contract card from your hand or field to the Graveyard.
D/D Swirl Slime	A polymerization on legs that can Fusion Summon a D/D/D Fusion Monster using D/D monsters from your hand as materials, including itself. It can also banish itself from the Graveyard afterwards to special Summon a D/D monster from your hand.
D.D. Warrior Lady	Same as D.D. Assailant (above). Also, this card had the option to remove the monster, or not to remove the monster. This card doesn't need to be destroyed by battle to remove the opponent's monster, just battling it will do, hence why this came off the list a while after Assailant.
Dante, Traveler of the Burning Abyss	A generic Rank 3 Xyz Monster that can easily fill the Graveyard with monsters, such as Burning Abyss and Phantom Knight monsters for easy advantage. Can replace or even recycle another copy of itself once it is sent to the Graveyard through any means, and can also be used to easily Xyz Summon Beatrice, Lady of the Eternal (Limited in the TCG). It also forms a small loop with Cir, Malebranche of the Burning Abyss (Limited in the TCG). Only hit in the OCG instead of other aforementioned cards, came back to 3 due to the lack of Burning Abyss decks topping in the OCG.
Dark Magician of Chaos	It's a strong monster with a very good effect; its effect even works when it's Special Summoned, making it more powerful than Magician of Faith, who is also Unlimited. Dark Armed Return Decks were godly with this card. However, this card was errata'd so that it can only retrieve one Spell per turn, during the end phase of when it's Normal or Special Summoned, allowing it to come off the list.
Dark Scorpion - Chick the Yellow	This + Makyura + Call of the Haunted = OTK, but Makyura is now Forbidden and this card is bad.
Dark Strike Fighter	Was formerly Forbidden due to being able to tribute any number of monsters on your field during either of your main phases to create easy OTK's, and a minimum of 4000 damage by itself in some cases. Now, they changed the effect so Dark Strike Fighter can only tribute one monster per turn during your main phase 1.
Debris Dragon	Highly usable with the number of Level 3 monsters with very low ATK like Lonefire Blossom, Dandylion, Card Trooper, etc. Can easily make LEVEL 7 Synchros like Black Rose Dragon, or higher-Level monsters like Trishula if Tokens are present on the field. Could also be abused in Dragon Ruler Decks (where it was searchable via Tempest) to Synchro Summon Star Eater or to bring back Flamvell Guard or The White Stone of Legend for Level 8 Synchro Summons in Dragon Ruler Decks. However, it does require a player's Normal Summon, making it far slower, and hard to reuse, so it came off the list.
Demise, King of Armageddon	See Demise/Doom OTK. The eventual lack of such Decks in the meta resulted in this card coming off the list.
Destiny HERO - Disk Commander	The effect is too powerful, turning ordinary revival cards into Pot of Greeds. There are way too many ways to revive it: Call of the Haunted, Monster Reborn, Limit Reverse, Kinka-byo, Graceful Revival, Soul Charge, Oasis of Dragon Souls, etc. Now, its draw effect can only be used once per duel, and furthermore, cannot be activated in the same turn it's sent to the GY.
Destiny HERO - Malicious	This card used to be good for easy Synchro Summon plays, but came off the list due to its lack of use in the evolving meta. Went back on the list later due to use in various Warrior Link Decks abusing Isolde, Two Tales of the Noble Knights, Summon Sorceress, and Firewall Dragon, but with the banning of the latter two cards (see above), it came off the list again.
Ehther the Heavenly Monarch	Key monster in Monarch Decks. Can Special Summon another Monarch from your Deck when it's tribute Summoned, while also setting up your Graveyard with cards such as Pantheism of the Monarchs or The Prime Monarch. It can even tribute Summon itself during the opponent's turn to disrupt their plays with The Monarchs Stormforth and Kuraz the Light Monarch. Came off the list as Monarchs are no longer relevant in the current meta.
El Shaddoll Construct	Key Fusion Monster in Shaddoll Decks along with El Shaddoll Winda (below). Sets up combos by sending ANY "Shaddoll" card from your Deck to the Graveyard once Fusion Summoned, can send useful LIGHT monsters from the Deck to the Graveyard when using Shaddoll Fusion, and can autokill any Special Summoned monster when it battles. Works well with both Fairy Tail - Snow (See above,) and Performage Trick Clown. Came off the list due to Shaddoll decks not being relevant anymore.
Elemental HERO Bubbleman	Mainly was Limited due to making combos and causing OTKs with Elemental HERO Stratos (Who is Forbidden in the TCG). Can easily make Rank 4 Xyz Summons or Fusion Summons with Miracle Fusion or Mask Change. Second effect can turn around games, but is rarely pulled off.
Elemental HERO Shadow Mist	Good Level 4 monster in HERO Decks that can search any Quick-Play "Change" Spell Card (mainly Mask Change or Mask Change II) when it's Special Summoned and can also search a HERO monster when it's sent to the Graveyard. Was Limited in OCG due to the unexpected splashability in most Decks. Now off the list as HERO decks aren't good anymore.
Elemental HERO Stratos	Great searcher whose effect triggers on Summon. No once per turn restriction allows it to create OTKs. You lose no advantage playing this card. Easily searched by other cards, such as A Hero Lives(See above), E - Emergency Call, Reinforcement of the Army(Limited), Summoner Monk, etc. Also, has a potent S/T destruction effect. Was a key part of the Airblade Turbo Deck, the top Deck of the September 2006 Format. However, HERO's aren't as good as they once were, so this came off the list.
El Shaddoll Winda	Key Fusion Monster in Shaddoll Decks along with El Shaddoll Construct (above). Restricts both players to 1 special Summon per turn and can't be destroyed by the opponent's card effects. Can be Fusion Summoned easily with Shaddoll Fusion, Nephe Shaddoll Fusion or El Shaddoll Fusion, all of which can also be recycled with this card's effect.
Evilswarm Exciton Knight	Generic Rank 4 Xyz Monster with a powerful destruction effect. Can nuke the field whenever you have less cards than your opponent, and the effect can even be chained to cards like Bottomless Trap Hole, Compulsory Evacuation Device, Torrential Tribute, etc. While it has low ATK and makes your opponent take no more damage that turn, the loss in card advantage when hit by this card's effect can be devastating, especially against Pendulum Decks. This card is Unlimited now due to the lack of use of Rank 4s in the Link era.
Evilswarm Ophion	Very powerful Rank 4 Xyz with high ATK. Can be Summoned very easily in Lswarm Decks with Evilswarm Castor, Evilswarm Kerykeion, Evilswarm Mandrago, and Rescue Rabbit. Seals special Summons of Level 5 or higher monsters, and can add any Infestation Spell/Trap card from the Deck to the hand, mainly Infestation Pandemic and Infestation Infection. Removed due to lack of Evilswarm decks in the metagame.
Exiled Force	Same as D.D. Assailant (above).
Formula Synchron	Easily Summoned with cards like Glow-Up Bulb (Forbidden in OCG, see above) and tokens made by Dandylion. An instant +1. Crazy when comboed with T.G. Hyper Librarian, who is Limited in the OCG. Can even be used for a Synchro Summon during the opponent's turn.
Gladiator Beast Bestiari	Required to Summon Gladiator Beast Gyzarus, and as a key means of S/T removal. However, Gladiator Beasts haven't done much in a long time, so it came down to 3.
Goblin Zombie	Very good searcher. In a Zombie Deck, it can be more abusable than Sangan or Witch of the Black Forest because of their revival power. Not many people would use 3 anyways and zombie Decks aren't topping anymore.
Gorz the Emissary of Darkness	Stops OTKs AND Special Summons a good Token. Turns games around with no real effort. Off the banlist due to lack of use and the release of better handtraps and Traps.
Goyo Guardian	Very high ATK for a Level 6 Synchro Monster. Good effect. Summons the opponent's monster right away so it can be used for Synchro/Xyz Summons. Now it has an erratum that now makes it only Summonable by EARTH tuner monsters. Even prior to that, its effect was eventually considered too slow to pull off in the current meta; plus the three successive formats following its ban (Xyz, Pendulum, and Link) weren't as exploitable by its effect, and in the case of the latter two, impossible; so it was inevitably going to come off anyway.
Green Baboon, Defender of the Forest	Before, it could be Special Summoned when a Beast was destroyed by battle or by a card effect. This was rather good with a relatively low cost for high ATK. Now they changed the ruling and it can't be used during the Damage Step, so destroying by battle won't Trigger its effect.
Grandsoil the Elemental Lord	Before, the lack of a once per turn restriction for its Special Summon effect allowed infinite loops. For example: with the proper setup, "Firewall Dragon" can return this card to the hand, then be used to Special Summon another "Firewall Dragon". This card can then Special Summon itself, and revive the spent "Firewall Dragon", which also resets its bounce effect. Can also be looped with cards such as Dewloren, Tiger King of the Ice Barrier (Limited) and Mist Valley Shaman. Came off the list after it's special summon effect was errata'd to once per turn, preventing any loops with it.
Green Gadget	Gadget Decks used to top frequently, but aren't as powerful as they once were. Most Gadget Decks wouldn't run more than 2 of each anyways.
Red Gadget
Yellow Gadget
Honest	Amazing effect. Allows your monster to run over any other monster, and deal decent damage. Easily reused with Beckoning Light. Abusable with BLS.
Ignis Heat, the True Dracowarrior	Allows easy searching and/or activation of True Draco and True King Continuous Spells directly from the deck, though this is less devastating than "Dinomight Knight, the True Dracofighter" as the effects of the Continuous Spells can only be activated during the player's turn.
Injection Fairy Lily	She was considered to be too fast and too strong for the format at the time. Now there are Decks other than beatdown types, so this came off.
Invoked Mechaba	Strongest Fusion Monster in the Invoked arsenal. Can negate the activation of any Spell/Trap or monster effect by discarding a card of the same type. Said cards are banished rather than destroyed afterwards, preventing several cards from gaining compulsory advantage, while also rendering said cards out of reach of most forms of retrival. Synergizes well with Artifact cards, or with already used handtraps like Effect Veiler or Ghost Ogre & Snow Rabbit. Came off the list as Invoked decks aren't relevant anymore.
Inzektor Dragonfly	This one card could swarm the field AND cause nasty loops in one turn with Inzektor Hornet, Inzektor Ladybug, Inzektor Hopper, or Inzektor Earwig. Second effect can be used multiple times in one turn to create OTKs. Can be searched easily with Sangan (pre-errata), Howling Insect, Insect Imitation, Transmodify, Downbeat, Inzektor Centipede, and Mystic Tomato. Can be reused with Inzektor Giga-Mantis or Inzektor Sword - Zektkaliber. However, Inzektors aren't relevant anymore, so this and Hornet (below) came off the list.
Inzektor Hornet	A solid one-for-one destruction card with perks. The key to Inzektors. Easy to dump into the Graveyard with Foolish Burial, Armageddon Knight, or Dark Grepher. You only need one to loop with anyway. Now off due to lack of Inzektor decks topping.
Jinzo	Very popular early in the game's history since back then the game was slow enough to allow for monsters to be Tribute Summoned. Then the metagame picked up speed, where Special Summons became more favourable, and Jinzo dwindled in popularity due to both Royal Decree and presence of better monsters to Special Summon, so it came off the list. Naturia Bamboo Shoot is also a Tribute monster, but it also stops Spells and not just Traps, although it is less splashable.
Judgment Dragon	Can be Special Summoned easily in Lightsworns. Low cost to nuke the Field except itself. 3000 ATK. Double JD is broken, especially when they can be returned to your hand with Beckoning Light. However, in the OCG with the new Priority ruling change, the increase of anti-Special Summon cards for high Level/LIGHT (chaos) monsters, and Lightsworns not topping much might have been the reason to unlimit it again.
Kozmo Dark Destroyer	The boss monster of Kozmo Decks. Can target and destroy any monster on the field when it's Summoned, and is chainable since the low-level Kozmo monsters can summon it during either players turn. Was also quite hard to remove due to its high ATK and invulnerability to the opponent's targeting effects. Also Special Summons another Kozmo monster from the Deck when it dies, and can even destroy itself to trigger this. Searchable by Kozmo Farmgirl and Kozmo Tincan, and reusable by Kozmotown and Kozmo Strawman. Came off the list due to lack of relevance of Kozmo decks.
Kuribandit	Splashable Level 3 monster with a good effect. Tributes itself to send the top 5 cards from your Deck to the Graveyard during the End Phase of turn it's Normal Summoned, while also retrieving 1 Spell/Trap among them (namely cards like Soul Charge, Foolish Burial, etc.) to your hand. Came back as it's effect is considered too slow for the current game.
Legendary Six Samurai - Shi En	Stops 1 Spell or Trap every turn. Very easily Summoned in Six Samurai. Can prevent himself from being destroyed if there's another Six Sam out. Came off the list due to the lack of Six Samurai in the meta, and the increasing prevalence of activatable Spell/Trap effects, such as Breakthrough Skill.
Light and Darkness Dragon	See Perfect Circle. Not as abusable now that Tribute Summoning is considered slow.
Lumina, Lightsworn Summoner	Easy effect that special Summons a Lightsworn monster from the Graveyard. Gives uses to cards that are useless in the hand (e.g. Wulf, Lightsworn Beast). Nice mill effect. Since Lightsworns aren't topping anymore, this came off the list.
Magician of Faith	Allows the player to reuse Spells Cards, mostly ones with broken effects like Harpie's Feather Duster (Forbidden in the TCG and Limited in the OCG), Dark Hole and Soul Charge (now Forbidden). Was part of the Goat Control and Tsukuyomi Lockdown Decks. Came off the list due to being too slow for the current metagame.
Manju of the Ten Thousand Hands	Adds any Ritual Spell or monster to your hand when Normal or Flip Summoned. Mainly hit due to abuse in the Nekroz archetype in the OCG.
Manticore of Darkness	There was an OTK with this card (but it's too inconsistent with the current format), and it worked well with Card of Safe Return (now Forbidden).
Marauding Captain	Same as D.D. Assailant (above).
Marshmallon	Relatively hard to kill. Instantly inflicts 1000 damage, which is quite a lot. However, Spirit Reaper went back to 3, so it was inevitable that this would also go back to 3 due to the high quantity of removal power.
Mask of Darkness	Well, Royal Oppression (now Forbidden) became Limited when this became Unlimited, not that anyone was using this card anyway. Used to be part of the Tsukuyomi Lockdown, but isn't anymore with Time Seal now Forbidden.
Mermail Abyssgunde	Key card in Mermail Decks. Special Summons any Mermail from your Graveyard when discarded to the Graveyard. Good monsters it can revive include Mermail Abysspike, Mermail Abysslinde, Mermail Abyssdine, Mermail Abyssmegalo, Mermail Abyssteus, or Mermail Abyssleed for easy combos and Xyz Summons. Can be searched by Mermail Abyssteus (below) and reused with Salvage or Mermail Abyssturge. Came off the TCG list due to the lack of Mermails in the current meta.
Mermail Abyssteus	Key card in Mermail Decks. Can be Special Summoned easily. Adds any Level 4 or lower Mermail monster from your Deck to your hand when Summoned by its effect. Can be searched easily with Abyss-sphere and reused with Abyss-squall or Mermail Abyssgunde (above).
Mezuki	Creates +1 Summons. Effect is easy to pull off and reuse. Staple in almost any Zombie Deck to generate loops and OTKs. Easily searchable with Foolish Burial or Lavalval Chain, and reusable with Burial from a Different Dimension. Was Unlimited since Zombies are no longer as good as they once were.
Miscellaneousaurus	Can allow Dinosaurs to operate without fear during the Main Phase, and can also search out a vast array of useful Dinosaurs. The downside to its second effect can be worked around with cards like Babycerasaurus and Petiteranodon, or exploited in conjunction with cards like Giant Rex and Tyranno Infinity. This card was Limited in the TCG instead of Dino searchers, but came off with the lack of use of that deck.
Morphing Jar #2	A very potent field-disruptor, freezing the battle phase and eating up Nomis, Tribute and Extra Deck monsters the moment it is flipped while resetting the field. Can create outrageous loops and OTKs/FTKs, especially with All-Out Attacks or Jackpot 7. However, there are plenty of ways to stop flip effect monsters nowadays, so it came off the list.
Necro Gardna	Easily used in Lightsworns, and reused with Burial from a Different Dimension Lightsworns have not been topping lately due to their relative inconsistency, so this was Unlimited to give them a chance in the current meta.
Nekroz of Brionac	Key card in Nekroz. Simply by discarding itself, it can search effectively ANY Nekroz card (including Spells, thanks to Nekroz of Clausolas). Can also be Summoned to return up to 2 monsters Special Summoned from the Extra Deck back to the Deck, easily clearing the field. Off due to lack of Nekroz decks.
Neo-Spacian Grand Mole	Can create locks, especially with Kaiser Colosseum (Forbidden in the TCG). Easily takes out boss monsters, particularly those with specialized Summoning requirements, and does not destroy or target. However, it needs to battle to use its effect, making it too slow for the current meta.
Number 11: Big Eye	Powerful Rank 7 Xyz Monster with a good effect. Can permanently take any opponent's monster, with no restriction about how it can be used, although it can't attack the turn it uses its effect. Was also used as an easy tribute to activate cards like Deck Devastation Virus and Eradicator Epidemic Virus (also unlimited, see below). Came back to 3 since the main Decks that Summoned this so easily are either dead (Dragon Rulers) or no longer relevant (Spellbooks and Mermails).
Performapal Pendulum Sorcerer	This card played a pivotal role in Performapal Pendulum Decks, as it could search out key Performapal cards while triggering the effects of monsters such as Performage Plushfire and Guiding Ariadne. It could also be used to Summon Performage Trapeze Magician, leading to easy OTKs.
Phantom of Chaos	Was formerly abused in Sky Scourge Norleras Decks. Once those Decks stopped doing well, this was allowed to go back to 3.
Plaguespreader Zombie	Universal reusable Tuner. Its downside can be overridden by playing a search card afterwards, thus shuffling your Deck. Was taken off the list due to zombie/Synchro Decks that used this not topping anymore.
Protector of the Sanctuary	Formerly abused with things like Time Seal and Yata-Garasu as an additional layer of insurance for such a lock since the opponent could only break the lock by drawing with a card effect. Time Seal and Yata-Garasu soon got Forbidden, leaving no reason to limit Protector of the Sanctuary.
Qliphort Scout	Adds any "Qli" card from your Deck to your hand once per turn, by paying 800 LP. Since that's just its Pendulum Effect, it's also treated as a Normal Monster so it can be searched easily itself via Summoner's Art or Saqlifice. However, Qliphorts aren't good anymore, so this came off the list.
Raiza the Storm Monarch	Raiza was overused in Monarch Decks, and that was Tier 1 back then. Later, Caius was released, alongside other faster Decks, so this got let off. Caius is now considered to be better anyways.
Reborn Tengu	Replaces itself when it leaves the field. Doesn't care about being Banished or Bounced, though it does when Spun or used as Xyz Material. Abusable in Synchro/Link Decks. Similar to Destiny HERO - Malicious, who is Semi-Limited.
Reflect Bounder	At the time they Limited this, Chaos Decks were Tier 1. The Envoys were also Forbidden at this time, but they realized that this didn't really need to be hit as hitting the Envoys was enough, so this later this came off.
Rescue Cat	Instant +1. Abusable by Gladiator Beasts, Naturias, Wind-Ups, Flamvells, Fableds, Madolches, Raccoons, and especially X-Sabers. Formerly Forbidden due to not having a once per turn restriction for its effect and not negating the effects of the Summoned monsters, allowing for easy OTK's with cards such as Uniflora, Mystical Beast of the Forest. Now, it can only be used once per turn and negates the effects of the Summoned monsters. Can easily be searched with Summoner Monk.
Rescue Rabbit	Super splashable in many Decks. Fire Fists, Evilswarms, Gem-Knights, Gladiator Beasts, and more all can use this for instant Rank 4 Xyz or Fusion Summons. Key card of Dino Rabbit Decks.
Sacred Phoenix of Nephthys	At the time when it was Limited, destruction effects were the metagame, especially with Gadget decks using it to the fullest extent possible. Nephthys could come back persistently, destroying backrow at the same time. Then the metagame picked up speed with both chainable Traps and Banishment Decks becoming more popular and widespread. Since then, Nephthys' usefulness has died down considerably, and is really only seen nowadays splashed in with Fire Kings, or with the new Nephthys cards.
Sangan	Universal searcher. Easily searched by Tour Guide From the Underworld and reused by Crane Crane. Adds a ton of consistency. Now it can only search once per turn, and prevents you from using the effects of the added card that turn.
Scarm, Malebranche of the Burning Abyss	Key searcher in Burning Abyss Decks. Searches any Level 3 DARK Fiend monster during the end phase of when it's sent to the Graveyard, mainly another Burning Abyss monster or Tour Guide from the Underworld (Limited).
Senju of the Thousand Hands	Same as Manju of the Ten Thousand Hands (above).
Shurit, Strategist of the Nekroz	Key card in Nekroz. Can be used to easily Ritual Summon the otherwise difficult to Summon higher Level Nekroz Ritual Monsters, and even searches any Warrior-Type Nekroz Ritual Monster on top of that. Its text also means it use its full requirement effect if banished for Nekroz Mirror. Can be searched easily with Nekroz of Brionac or Reinforcement of the Army and reused by Nekroz of Unicore or Dance Princess of the Nekroz (after banished by Nekroz of Valkyrus or one of the Nekroz Ritual Spell cards). However, it's not as good as it once was, and Unicore as well as Djinn Releaser of Rituals are still Limited and Forbidden, respectively.
Sinister Serpent	Free discard for costs, etc. Turns discarding into a +0. Really annoying to be against with The Dark Door. Can be sent from your Deck to the Graveyard through Foolish Burial (Limited). Now, it'll Banish itself from your Graveyard at the end of your opponent's turn if it's still there by then, unless cards like Imperial Iron Wall and Chaos Hunter are active.
Snipe Hunter	Formerly abused in Gadget Decks due to massive hand advantage to fuel its effect. The lack of Gadget Decks around resulted in it coming off the list.
Spirit Reaper	Can't be destroyed by battle, but unlike Marshmallon, it destroys itself the moment it is Targeted. Its other effect is great, except against Dark World, which is not relevant. Came of the list due to its lack of use in the meta.
Spore	Related to Glow-Up Bulb, who is also Unlimited in the TCG. Universal Tuner. Very potent Level altering effect. It is currently unknown why this card didn't go to Unlimited in the September 2012 format (its effect can only be used once per Duel, so no one ran more than one).
Star Seraph Sovereign	Key card in the Seraph engine. Allows for easy combos, pluses, and Rank 4 Xyz Summons when used in combination with other Seraph cards or Tellarknights.
Summoner Monk	Great searcher. Was originally hit because it could grab Rescue Cat. Combos well with Sacred Crane, as well as Shaddolls, Tellarknights, Star Seraphs and Elemental HERO's Shadow Mist or Stratos. Easy Rank 4 Xyz Monster/Level 8 Synchro Monster.
T.G. Hyper Librarian	Super splashable, low Level Synchro with decent ATK. Good effect that works when either player Synchro Summons. Broken when comboed with Formula Synchron, but Master Rule 4 makes this harder to pull off now, so it came off the list.
T.G. Striker	A Cyber Dragon-like Level 2 Tuner. Can start fast Synchro Summoning variety without using the Normal Summon. Came off the list due to its lack use in the Meta.
The Agent of Mystery - Earth	It's like Stratos for Agents, and he's Limited in the TCG. It's also a Tuner. Came off the list due to Agents not being relevant anymore.
Thousand-Eyes Restrict	Had a once powerful lockdown effect. Was part of the Goat Control Deck. Easily Fusion Summoned with Instant Fusion, or previously Metamorphosis. Easily revived because of its low ATK and low Level (e.g. Graceful Revival and Limit Reverse). You can use Instant Fusion, use its effect, then Tribute it for a Monarch or Link it off. However, this is slow for the current meta, so it came back to 3.
Thunder King Rai-Oh	Low Level, high ATK, seals search effects, and can negate a Built-in Special Summon. Great counter against most current Decks in the meta, which rely on both of the above. There are methods of getting around it, however.
Toadally Awesome	Strong Rank 2 Xyz Monster with many good effects. Can Special Summon a Frog monster from your Deck by detaching a material during either player's Standby Phase, can negate any opponent's card by sending an Aqua monster from your hand or field (even itself) to the Graveyard AND set that negated card to your field, and can recycle any WATER monster from your Graveyard (even itself) when it's sent to the Graveyard. Mainly hit due to Paleozoic Decks that were topping frequently due to this card in the OCG. Can also be splashed in some Rank 4 Decks that can Xyz Summon Bahamut Shark. However, Paleozoic/Frog Decks aren't topping anymore, so this came off the list.
Tragoedia	Stops OTKs AND has other great effects. Can get very strong, can take opponent's monsters, or even alter its own Level for Synchro/Xyz shenanigans.
Treeborn Frog	Yes it's a free Tribute, but you can only activate 1 anyway. So, Limiting isn't going to do much. Came off due to Frogs not being relevant anymore.
Tribe-Infecting Virus	Was formerly forbidden due to being able to clear the entire field with its effect, but Raigeki (Limited) and Dark Hole are considered better since they don't use your normal summon and don't have a discard cost either. Combos well with Mermails and Atlanteans, and can be searched easily with Summoner Monk, but neither of those are relevant anymore.
Trishula, Dragon of the Ice Barrier	Was once the best Synchro monster in the game. Easy to drop in most Synchro-based Decks. Banishes a card from 3 different places without targeting. Agents could also drop it easily. The loop in Infernities to drop it infinite times may have been a contributing factor as well. However, Synchro decks aren't as good as they once were, so this came off the list.
Tsukuyomi	Reusable Book of Moon effect. Was part of the Tsukuyomi Lockdown, but not anymore with Time Seal Forbidden. Not as good as it once was, so it came off the list.
Twin-Headed Behemoth	Monarch Decks used to run 3 at the time, keeping a monster to Tribute on the field whether it was destroyed by battle or by a card effect. Then a new ruling was made: "The effect of "Twin-Headed Behemoth" can only be used ONCE throughout the entirety of the Duel. Even if your Deck includes three copies of the card, between those three copies the effect can only be used once, not once each." This card became Unlimited after that ruling was released, and Monarchs then received Treeborn Frog (see above) and that replaced this card, even if the ruling wasn't made.
Vampire Lord	See Sacred Phoenix of Nephthys (above).
Wind-Up Magician	Summons a Wind-Up monster from the Deck whenever a Wind-Up Monster’s effect activates. The "Once while face-up on the field" restriction is easily overridden by Summoning another copy of itself and activating another effect afterwards. Crazy when combo-ed with Wind-Up Shark. Can be searched easily with Summoner Monk and Wind-Up Factory. Creates easy Xyz Summons. It can clog up your Main Monster Zones when overused, though.
Wind-Up Shark	Can be special Summoned whenever another Wind-Up monster is Summoned. Can be searched easily by Summoner Monk and Wind-Up Factory. Works very well with Wind-Up Magician. Creates easy Rank 3-5 Xyz Summons.
Windwitch - Ice Bell	Can Special Summon itself whenever you control no monsters, and can then Special Summon "Windwitch - Glass Bell" from your Deck (which can then search and Special Summon "Windwitch - Snow Bell"). Afterwards, you can Synchro Summon "Windwitch - Winter Bell" with this card and "Glass Bell", and then "Crystal Wing Synchro Dragon" with "Winter Bell" and "Snow Bell", which will be immune to destruction by card effects due to "Snow Bell".
Wisdom-Eye Magician	Key card in the Magician Pendulum engine. Can destroy itself to search ANY Magician Pendulum monster in its place, while stashing itself away later for a Rank 4 Xyz or Odd-Eyes Fusion Summon. Can be searched easily with Pendulum Call or Performapal Skullcrobat Joker (Forbidden in the TCG) or Odd-Eyes Pendulum Dragon, and easily reused with Nobledragon Magician.
Witch of the Black Forest	Much more powerful than its counterpart Sangan, since it's able to search out strong key monsters such as Dark Armed Dragon, Monarchs, Fire Fists, Hieratics, Bujins, Thunder King Rai-Oh, etc. AND most of the cards Sangan can search. Can be searched easily itself with Summoner Monk and some of the Prophecy/Spellbook cards. Dropped off the list due to an erratum that prevents you from using the effects of the added card that turn, similarly to Sangan.
Advanced Ritual Art	See Heralds combo and Demise/Doom OTK Decks. Not as broken as it used to be since the game got faster.
Black Whirlwind	Gives major hand advantage to Blackwing Decks. However, Blackwings haven't been competitive in the meta in a long time, so it was brought back to 3.
Book of Moon	Was one of the best Anti-Meta cards in the game. Stops just about everything and is one true Swiss Army Knife card. With Ignition Effect Priority being revoked, Book of Moon can easily render these monsters harmless and vulnerable by immediately responding to their Summons. It can also benefit you by flipping your monsters back face-down (See Empty Jar). Came off as stopping just one monster with it isn't considered as good anymore.
Book of Taiyou	Formerly abused in Empty Jar Decks to force the activation of Cyber Jar, Morphing Jar, and Morphing Jar 2. They aren't topping anymore, so this came up to 3. Also, Cyber Jar is Forbidden now anyways, and so is Morphing Jar #2 in the TCG.
Brain Control	Was formerly Forbidden due to being able to take control of any face-up monster your opponent controls for the small price of 800 LP. Now, it can only affect monsters that can be Normal Summoned/Set, which some decks might never use.
Burial from a Different Dimension	Can reuse monsters like Mezuki, Plaguespreader Zombie, Necro Gardna, Blackwing - Vayu the Emblem of Honor, etc.
Called by the Grave	Was Semi-Limited due to its ability to stop handtraps, allowing various toxic combos to go through unchecked. With Firewall Dragon Forbidden, this card came back to 3.
Charge of the Light Brigade	It's like ROTA (Limited), but for Lightsworns. It also mills. Lightsworns became irrelevant enough for this to drop off the list.
Creature Swap	Formerly considered too strong for the meta back when there weren't as many removal cards, also it's useless if the opponent uses evasion tactics to remove the monster you wanted to take, or if said monster requires archetype specific resources to be useful.
Dark Hole	Powerful and with no cost, but floating effects make it weaker than it once was, and Raigeki is often preferred over it anyways. However, triggering your own floating effects as well can be lethal.
Destiny Draw	Works very well with Destiny HERO - Malicious and is a godsend to Diamond Dude Turbo. Was a Semi-universal draw engine. Lack of relevant Destiny HERO monsters in general caused this card to come off the list.
Domain of the True Monarchs	A powerful Monarch support card that shuts down numerous Decks that rely on their Extra Deck. It also allows players to Summon powerful Tribute monsters such as Erebus the Underworld Monarch for only one Tribute.
Dragon Ravine	Can be used to search any Level 4 or lower Dragunity from your Deck to your hand OR act as a Foolish Burial to send any Dragon from your Deck to the Graveyard for easy Graveyard setup once per turn. Can be searched easily with Terraforming (Limited in the OCG) and Metaverse. Mainly Forbidden to try to kill Dragon Rulers, but with the Dragon Rulers now Forbidden themselves, it became Unlimited again.
Dragon Shrine	A Foolish Burial for Dragons (below). Additionally, if you sent a Normal Dragon to the Graveyard with this, you can send another Dragon-type monster to the Graveyard as well. Mainly hit to slow down Dragon Rulers in the OCG but with them now Forbidden, it was Unlimited.
E - Emergency Call	Searches ANY Elemental Hero, including Stratos (who is Limited/Semi-Limited in the TCG/OCG respectively), who then searches something else. With ROTA at 1, A Hero Lives at 3, and Pot of Duality at 3, HEROs had way too much search power, and it allowed them to run ridiculously low monster counts.
El Shaddoll Fusion	Key Fusion Spell in Shaddoll Decks. As Quick-Play Spell you can activate it any time you want, including the Battle Phase to make easy OTKs. Shaddolls haven't been good in a while though, and its card advantage is often unfavorable when compared to Shadoll Fusion.
Emergency Provisions	Formerly abused with Mirage of Nightmare, which is now Forbidden. Combos well with Good Goblin Housekeeping to draw several cards from your Deck at once.
Fire Formation - Tenki	Basically Reinforcement of the Army (Limited) for Beast-Warriors. Adds lots of speed to several Decks, like Constellars, Gladiator Beasts, Wind-Ups (for Wind-Up Rabbit), Bujins, Fire Kings, Koa'ki Meirus and especially Fire Fists, where it can search just about any Fire Fist monster from your Deck to your hand, and can be searched easily itself with most Fire Fist cards. Can also act as fuel for Fire Fist monster's effects and gives all beast-warriors 100 ATK. Initially Unlimited due to Fire Fists not being as good as they once were. Went back on the OCG list again when Zoodiac Decks were topping, but the banning of Broadbull and Drident were enough to wipe them out: so it's now Unlimited again.
Fissure	A 'one for one' card that was rarely used outside of Gadget Decks, and faster Decks that could cope were made, so this came off.
Future Fusion	Allows for massive Graveyard setup, particularly using Machines, Dragons, Worms, Zombies, and Infernoids, where Chimeratech Overdragon, Five-Headed Dragon, Worm Zero, Dragonecro Nethersoul Dragon and Infernoid Tierra respectively can allow for a large number of monsters of the player's choice to be dumped. Both HEROs and Fluffals abuse this with Miracle Fusion and Frightfur Fusion, respectively. However, this card now has an erratum so that it must send the Fusion Materials during the Standby Phase after it is activated, making it slower and easier to remove.
Hieratic Seal of Convocation	Similar to E - Emergency Call, but with Hieratics. Opening with it pretty much meant you would OTK.
Instant Fusion	Instantly Fusion Summons any Level 5 or lower Fusion Monster from your extra Deck for easy Synchro or Xyz Summons. Mainly hit due to a two-card FTK involving this card and Elder Entity Norden but with Norden now Forbidden, this came off the list.
Interrupted Kaiju Slumber	Similar to Dark Hole, but can also Special Summon as many Kaiju monsters as possible to either player's field, allowing for multiple different combos and OTK's. Prior to the errata of the latter, it allowed for an easy 3300 damage by Special Summoning Super Anti-Kaiju War Machine Mecha-Dogoran to the opponent's field. Can also search any Kaiju on a later turn for spot removal, and be searched by The Kaiju Files. However, Kaiju's aren't relevant anymore, so this came off.
Level Limit - Area B	Excellent stalling device for no cost, effectively locking out most Decks that use lots of high-Level monsters. However, it does not affect Xyz Monsters, also most stall cards are bad now. Similar to Gravity Bind, which also went back to 3.
Lightning Vortex	Limited due to abuse with Sinister Serpent for cheap frying of the opponent's face-up monsters. It still saw some abuse since there were 2 Night Assailants still on the list. It finally came off the Limited status after Night Assailant hit 1 on the next list.
Limiter Removal	Creates easy OTKs in Machine Decks. Most of the time your monsters won't be destroyed during the End Phase because you can just Synchro/Xyz/Link Summon with them. Came off due to lack of use in the meta.
Mage Power	Was considered too strong back when beatsticks won Duels on their own. Equip cards are considered slow now and they most likely won't stick around with S/T removal cards being popular these days.
Magical Stone Excavation	Allows quick reuse of major Spell Cards. Its heavy cost is often circumvented in Diamond Dude Turbo Decks. Empty Jar Decks love this, but with Morphing Jar #2 and Morphing Jar becoming Forbidden in the TCG, those Decks are unplayable now, so it came off the list.
Megamorph	Doubling original ATK can be a lot, sometimes enough to OTK. The drawback of halving ATK when you have more LP isn't too bad either as you can always equip it to your opponent's monsters. However, Equip Spells are still bad and have gotten worse now with s/t removal, also beatsticks don't mean as much anymore.
Monster Gate	Similar to Reasoning (Limited, see above), but requires a tribute. Used a lot by Turbo and OTK Decks. Abusable in Hieratics and Infernoids. Now Unlimited since it's not as good as it once was, and Reasoning is usually better anyways.
Mystical Space Typhoon	Was formerly the best chainable S/T removal card in the game, but it's not as strong as it once was, and today it's outclassed by Cosmic Cyclone, Hey, Trunade! and Twin Twisters, the former two of which do not destroy, and the latter can destroy two cards instead of one.
Nekroz Cycle	Key Ritual Spell in Nekroz Decks. In addition to being able to Ritual Summon any Nekroz Ritual Monster from your Graveyard (allowing easy use of both of their effects) as well as your hand, it can also banish itself and 1 Nekroz monster from your Graveyard to add 1 more Nekroz Spell Card from your Deck to your hand if you control no monsters.
Nobleman of Crossout	Was formerly considered to be too powerful back when most Decks couldn't do more than set a monster before ending their turn. Like Fissure (above), faster Decks that could cope with one for one cards like this were made over time, so this later came off the list.
Overload Fusion	Back then, Future Fusion comboed with this to provide a large beatstick; nowadays, beatsticks don't mean as much as they once did, and Future Fusion has been slowed down.
Pot of Duality	Lets you choose one of the 3 top cards of your Deck without losing hand advantage. Sets up for big plays. Adds a lot of consistency. But, it's too slow for the current meta.
Preparation of Rites	Adds any Level 7 or lower Ritual Monster from your Deck to your hand, and can recycle a Ritual Spell card from your Graveyard. Mainly hit due to abuse with Nekroz, but later dropped after they stopped topping, and Pre-Preparation of Rites is often better since it can add both the Ritual monster and it's respective ritual spell card from your deck to your hand.
Rekindling	Very powerful Spell Card. Can Special Summon as many FIRE monsters from your Graveyard with 200 DEF as possible. Powerful plays with it include reviving multiple copies of Laval monsters like Volcano Handmaiden, Magma Cannoneer, Lancelord, Forest Sprite (which can all be easily sent to the Graveyard via Molten Conduction Field) to easily Synchro Summon Shooting Quasar Dragon or Red Nova Dragon, Brotherhood of the Fire Fists Spirit and Leopard to Synchro Summon another Brotherhood of the Fire Fist - Horse Prince, Fire King monsters like Avatar Yaksha and Avatar Barong to make easy Rank 4 Xyz Summons, and Infernoid Decatron, to dump multiple Infernoids in the GY while enabling Link Summons, allowing further branching plays. However, most of the decks that once used this aren't topping anymore, so it came back to 3.
Royal Tribute	Particularly disruptive when used on the first turn, leaving one vulnerable and unable to retrieve what has been lost because of Necrovalley. You no longer see their hand by default, however. Gravekeeper's and Necrovalley aren't relevant anymore, so this came off with them.
Saqlifice	Key Spell Card in Qliphort Decks. Prevents the equipped Qliphort from being destroyed in battle, also it gains 300 ATK and is treated as 2 Tributes for the Tribute Summon of a Qliphort monster, mainly Qliphort Disk (who then Summons 2 more Qliphorts from your Deck for an easy OTK). Can also add a Qliphort Monster from your Deck to your hand when it's sent from the field to the Graveyard. Searchable and reusable via Hidden Armory.
Sacred Sword of Seven Stars	Similar to Allure of Darkness, which is also unlimited, but could be abused with Dragon Ruler monsters to trigger their effects when banished by this card's effect. However, with the Dragon Rulers now Forbidden, this came back to 3.
Shien's Smoke Signal	Grabs key Samurais like Kageki and Kagemusha. Came off the list due to the lack of Six Samurais in the meta now.
Smashing Ground	Fissure became Unlimited in the format before this came down, so this followed.
Spellbook of Fate	Chainable, powerful Spell card in prophecy Decks that can get over almost anything. Can easily banish an opponent's card without Targeting by banishing 3 Spellbook Spell cards from your Graveyard (which can act as setup for Spellbook of Eternity), or can flip Spellbook Magician of Prophecy face-down to reuse its effect again. Can be recycled with The Grand Spellbook Tower or Spellbook of Eternity (after banished with another copy of Fate or High Priestess of Prophecy).
Spellbook of Knowledge	Can draw 2 by sending any Spellbook card with a different name of it or a Spellcaster you control to the GY, though you can only activate 1 per turn. Mainly hit due to a splashable draw engine consisting of this card, "Spellbook Magician of Prophecy", and "Spellbook of Secrets". This card is Unlimited in the TCG.
Super Rejuvenation	Amazing draw card. Makes strong discard-and-draw cards even stronger. Offsets the costs of certain card effects. Can draw out most of your Deck in one turn if used right since it can be used multiple times per turn. Abusable in Exodia, Hieratic, and Dragon Ruler Decks. Trial and Tribulation was designed to be a fair version of this card. However, decks that constantly discard/tribute dragons aren't as relevant anymore, especially with the Dragon Rulers now Forbidden, so this came off the list.
Swords of Revealing Light	Stalls for quite a long time. You can still attack while the opponent cannot. Came off the list due to Stalling cards being bad now.
Temple of the Kings	Was formerly Forbidden due to being able to create easy Trap FTK's due to the lack of a once per turn restriction. Now the first effect has been errata'd to once per turn. The second effect can summon any monster from your hand, deck, or a fusion monster from your extra deck, which can work well with Phantom of Chaos, but it's very hard to pull off consistently in the current meta.
The Monarchs Stormforth	Allows you to Tribute monsters your opponent controls for Tribute Summons without targeting in an open Game state. Can even be activated during your opponent's turn to disrupt their plays with Ehther the Heavenly Monarch (Limited in the TCG), making cards like Forbidden Lance the only surefire way to safeguard their field. Can be searched by Pantheism of the Monarchs(Limited) or Tenacity of the Monarchs. However, Monarchs aren't as good as they once were, so this came off the list.
The Phantom Knights' Rank-Up-Magic Launch	Allows you to special summon any DARK Xyz monster by using another DARK Xyz monster you control with no materials as Xyz material. Since it is chainable, you can use it during your opponent's turn on a DARK Xyz monster, such as Time Thief Redoer, you control with no materials to easily summon Outer Entity Azathot (now Forbidden, see above) for a lockdown. It can also be used on Odd-Eyes Rebellion Dragon thanks to Odd-Eyes Absolute Dragon to bring out D/D/D Duo-Dawn King Kali Yuga. You can also easily summon True King of All Calamities or Raidraptor - Ultimate Falcon. Searchable by the combo of The Phantom Knights of Rusty Bardiche (now Forbidden in the TCG, see above) and The Phantom Knights of Silent Boots. Came off the list as Azathot got Forbidden, and it is slightly less searchable now that Rusty Bardiche is Forbidden as well.
True Draco Heritage	Grants excellent advantage; it can potentially draw three cards in a turn, allow the player to Tribute Summon an extra monster, and if sent to the Graveyard, can destroy a Spell/Trap, including the player's own, thereby either removing an obstacle or generating even more advantage.
Union Hangar	A strong field Spell card that can search out any LIGHT machine union monster when it's activated and can also equip a LIGHT machine Union Monster from your Deck to a LIGHT machine union monster that is Normal or special Summoned. Mainly hit due to ABC Decks that were topping in the OCG because of this card. Can be searched easily by Terraforming (See above).
United We Stand	Yes it makes monsters into bigger beatsticks, but with so many cards to stop it (e.g. Book of Moon, Dimensional Prison, Mystical Space Typhoon, etc.) it came off the list.
Wavering Eyes	A powerful, chainable card for and against Pendulum Decks. This card's first effect allows easy burn damage, the second effect is versatile and easy to trigger, while the third effect provides easy, generic removal. It was especially powerful in Pendulum mirror matches, where the player with Wavering Eyes can devastate their opponent's set up while furthering their own plays, or even chain their Wavering Eyes to their opponent's Wavering Eyes, effectively rendering theirs useless. However, the release of Link Monsters and Master Rule 4 weakened this card's power significantly, since you must use your left and right Spell and Trap zones as Pendulum Scales now, and unless you control a Link Monster, you can only Pendulum Summon monsters from your Extra Deck one or two at a time.
Abyss-sphere	Great searcher. Special Summons ANY Mermail from your Deck. Can quickly Summon Mermail Abyssteus, Mermail Abyssmegalo, or Mermail Abyssleed for Rank 7 Xyz plays. Works very well with Mermail Abysslinde. Can be searched easily by Mermail Abyssmegalo. The lack of Mermail Decks being competitive caused this card to leave the list.
Bottomless Trap Hole	Very powerful 1-for-1 card. Banishes the monster upon Summon. Was a staple in most Decks. With the removal of Ignition Priority, this card is even better than before. Because it says "when your opponent Summons a monster(s)," if your opponent Summons multiple monsters at once (such as a Pendulum Summon), they all get hit. Can be searched and reused by some of the Traptrix cards. Came off the list due to the general weakening of Traps in the current metagame, and the fact it is non-chainable doesn't help either.
Call of the Haunted	Much fairer speed when compared to its Spell counterparts. It can't be abused multiple times per turn (unlike Premature Burial). It can only special Summon from your own Graveyard (unlike Monster Reborn). Played a crucial role in the Dark Scorpion/Makyura OTK. Like Magic Cylinder, top Decks eventually didn't play this card much, so it probably came off the list for the same reason. Most Decks that ran it never used 3 anyway.
Ceasefire	Chainable, defuses Flip Effects, and unlike its close cousins, checks both sides of the field. With swarming of Effect Monsters being all the rage these days, Ceasefire can be particularly punishing, dealing up to 5000 damage in one shot. With the release of Master Rule 4 and Extra Monster Zones, the maximum possible damage has been upped even further to 6000. Is quite possibly the best burn card in the game, but Chain Burn decks with this card haven't topped in a while, so this came off.
Compulsory Evacuation Device	An easy out to most monsters, especially Extra Deck ones. With Priority revoked, this card has become even more powerful. Can also be used on your own monsters to save them from Dark Hole, Torrential Tribute, etc. Came off the list for similar reasons to Bottomless.
Crush Card Virus	Could formerly kill almost every monster your opponent had in their hand, field, and next 3 draws when it was played, but now the effect has been errata'd so that it only destroys monsters with 1500 or more ATK on the opponent's field and hand when activated, with no further Lingering Effects, while also letting the opponent destroy 3 monsters with 1500 or more ATK from their Deck, potentially setting up their Graveyard. Furthermore, the opponent takes no damage until the end of the next turn.
Deck Devastation Virus	Can take out universal searchers and the monsters they bring out. Its tribute requirement can be easily met, especially in Dark World Decks.
Dimensional Prison	Easily banishes an opponent's monster with nothing but the opponent attacking. Gets over many monsters that have destruction immunity effects, as it banishes and does not destroy. Like Mirror Force (below), the current meta's far too fast for it now.
Drop Off	This card got Limited at the same time Time Seal initially got Forbidden. Then they realized that stopping a Draw is completely different from discarding a drawn card, in Decks which use the Graveyard more often. Also unlike Time Seal, it can't be chained, meaning your opponent can't lose card advantage in their attempts to target it.
Eradicator Epidemic Virus	Lets you look at your opponent's hand for 3 turns. Stops their Spells or Traps for a long period with an easy-to-pay cost in almost all Decks, with the releases of Number 66: Master Key Beetle and Number 85: Crazy Box. Extremely abusable in Dark World Decks with Grapha, Dragon Lord of Dark World, in Evilswarm Decks with Evilswarm Ophion, and in Dragon Ruler Decks and their variants with Number 11: Big Eye and REDMD. Two of these together can shut down all non-monster cards. But, Traps in general are now bad.
Exchange of the Spirit	Was formerly one of the most notorious FTK cards in the game, allowing you to Deck out your opponent with this card alone once you filled your Graveyard with 15 or more cards then flipped this, or activated it on your turn if you used Makyura (Forbidden) or Temple of the Kings (also Unlimited). Now, it can only be used once per Duel, and can only be used when both players have 15 or more cards in their Graveyard, not just you.
Geargiagear	Key card in Geargia Decks. Special Summons any two Geargiano monsters from your Deck at no cost, and it also increases their Levels by 1 for easy Rank 4 Xyz Summons, or for Synchro Summons with Karakuri tuner monsters or Genex Ally Birdman (who is Limited).
Good Goblin Housekeeping	Back then, this Draw power was extremely good. It's bad now.
Gravity Bind	Stalls a lot, but Xyz Monsters aren't affected by it (Rank ≠ Level), also stall cards are bad now.
Icarus Attack	Powerful Chainable 2 for 2 card, which made Blackwings lethal. Now that they aren't topping much, and with S/T removal being popular, this came off the list.
Infernity Barrier	Powerful Trap card in Infernity Decks that negates almost anything. It's very easy for the opponent to meet its activation requirement since they don't have any cards in their hand most of the time, though near useless if they only have Infernity Necromancer, or similar monsters with low ATK. Can be searched easily by Infernity Archfiend. Infernity's haven't been good in a long time, though, so it eventually fell off the list.
Magic Cylinder	Negates an attack and inflicts major burn damage. Finishing move. Moved off the Limited List due to its lack of use in the meta.
Mind Crush	1 for 1 card. You don't really need to be a psychic to use this card, as you can easily call a card name after the opponent has used a search/retrieval effect, like Salvage, Machina Gearframe, Gadgets, etc. Allows you to see opponent's hand. Also, this card owns Ritual Monsters, when they activate their Ritual Spell Card, chain this and call the name of their Monster; a 2 for 1. The intended "downside" of calling a card wrongly can also benefit Dark World/Fabled cards. The lack of overall use in the meta perhaps resulted in it coming off the list. Like Magic Cylinder and Call of the Haunted (above), most people wouldn't use 3 anyway.
Mirror Force	Solid game changer, although with Starlight Road and THRIO out you need to be more careful when using this card. Came back to 3 due to lack of use in the meta, monster destruction being less powerful, Spell/Trap destruction being more common, and many better variants of this card have been released since.
Needlebug Nest	Mills the top 5 cards from your Deck to the Graveyard for easy Graveyard setup. Mainly hit due to abuse in Shaddolls, Lightsworns, and Dragon Rulers, all of which were topping in the OCG at that time.
Ojama Trio	Clogs the field with nigh-unusable Tokens, though they can be removed via a Synchro/Link Summon. Key card in Burn Decks. Came off with Link Summoning's introduction.
Reckless Greed	Because the skipped Draw Phases by its effect weren't accumulative, you could use multiple to draw many cards and win before the downsides kicked in. Too slow now.
Ring of Destruction	Was formerly Forbidden for causing too many draws in Tournaments and messing up Ranked Games. Instant destruction and serious burn. Lethal when combined with cards like Barrel Behind the Door or Spell of Pain. However, the effect has now been errata'd so it can only be used during the opponent's turn, can only be used on an opponent's monster with equal to or less ATK than the opponent's LP, and makes you take damage first, so it can't force tied games.
Royal Decree	1 card to continuously stop a large number of cards. Works well in Herald Decks to prevent the activation of Counter Trap Cards.
Sinister Shadow Games	Strong Trap card in Shaddoll Decks. Sends any Shaddoll monster from your Deck to the Graveyard AND can flip face-up a Shaddoll monster on your field, allowing you to get the effects of both the sent monster and the flipped monster. However, it's not a true Shaddoll card, and thus cannot be searched by Shaddoll Hedgehog, or reused by any of the Shaddoll Fusion Monsters. Besides, Construct's ban was a big enough hit to kill Shaddoll's relevancy.
Solemn Judgment	Can negate almost anything, having a cost you can always pay. However, Traps aren't as good as they once were so this came off in an attempt to slow the game down. Still extremely powerful.
Solemn Strike	Powerful Counter Trap Card that can negate any Special Summon or monster effect for only 1500 LP. Can be somewhat better than Solemn Warning (Limited) due to its lower cost and somewhat broader negation pool, and easily searched by cards like Guiding Ariadne and Sacred Arch-Airknight Parshath. Came off the list as traps are less effective now.
Solemn Warning	A lot of effects that Special Summon are present in the game. Paying 2000 LP to use this card is almost always worth breaking a loop that would otherwise generate several large monsters. It can also counter Normal Summons, making this card able to stop most turns in their tracks. However, Traps aren't as good anymore, so this came off the list.
Soul Drain	Many Decks rely on Graveyard and banished effects in the current meta. This card could easily defeat an entire Deck, especially Dark World Decks. However, it isn't considered as good as Macro or Fissure anymore, plus traps in general are now bad, so this came off the list.
The Transmigration Prophecy	OCG stall Decks used this with D.D. Borderline. Also, it was at 1 so it couldn't loop with another copy of itself. Pot of Benevolence does the same thing, but that can't be chained to an effect, and that banishes itself so it can't return another copy of itself. Came off the list due to looping it being too slow for the current meta.
Torrential Tribute	Punishes over-extending, but can easily be stopped with Starlight Road and THRIO in most situations. Came off for the same reasons as Bottomless and CED.