Chaos

Chaos is a series of monsters combining LIGHT and DARK. The most recognized cards in the series include:
 * Chaos Emperor Dragon - Envoy of the End
 * Black Luster Soldier - Envoy of the Beginning
 * Chaos Sorcerer

"Chaos Emperor Dragon - Envoy of the End" was the first of this trio to be sent to the Forbidden list, in September 2004. Chaos Emperor Dragon - Envoy of the End is known as one of, if not THE most broken card of all time. This card helped form the Yata-Garasu Lockdown, a very deadly and broken Deck, by using "Sangan" or "Witch of the Black Forest" with its effect to bring "Yata-Garasu" into your hand. The finishing blow required you to Summon, attack, and Lockdown your opponent, leaving them with no cards in their hand or on their field and leaving them unable to draw additional cards.

Chaos still continued to dominate the Metagame for the next 12 months. 2005 saw a Chaos Phoenix Deck using "Black Luster Soldier - Envoy of the Beginning" and "Sacred Phoenix of Nephthys" which proceeded to win the 2005 World Championship. This showed people that "Black Luster Soldier - Envoy of the Beginning", even if Limited to 1, was still far too powerful to be allowed to be used in Advanced Format. In September 2005, "Black Luster Soldier - Envoy of the Beginning" was Forbidden, but is now back with the release September 2011 ban list.

The next 12 months saw the emergence of the strongest Chaos metagame since "Invasion of Chaos". This style of Chaos revolved around "Chaos Sorcerer", which was still Unlimited, combined with the flexibility and power of the Monarchs. "Chaos Sorcerer" was eventually Forbidden in September 2006.

The Chaos ideal was left untouched until the release of "Force of the Breaker", where the Chaos era was reborn with the "Sky Scourges", two monsters whose effects were based on "Chaos Emperor Dragon - Envoy of the End" and "Black Luster Soldier - Envoy of the Beginning", with a third that was able to "choose" between the effects of "Jinzo" or "Spell Canceller". Neither of the new Chaos replacements made much of an impact, and have long since been condemned to the unused Card Pool on account of their Summoning Conditions being unworkable and situational. More recently, a Deck based around "Sky Scourge Norleras" and "Phantom of Chaos" has been seeing more play after it topped a regional (September).

Chaos has seen a return with the Semi-Limiting of "Chaos Sorcerer" in the OCG's September 2009 Lists and the use of "Dark Armed Dragon" and "Judgment Dragon". However, "Chaos Sorcerer" was back to being limited in the OCG's March 2010 Lists. In the September 2010 Lists, "Chaos Sorcerer" was back again to Semi-limited. "Chaos Sorcerer" has been unlimited in the March 2011 Lists.However, it was back to limited again in the September 2012 Lists. In the following September 2011 Lists, Black Luster Soldier - Envoy of the Beginning was Limited after 6 years of being Forbidden. This may lead to the return of Chaos decks to competitive play in the upcoming format.

A new Synchro Monster, "Chaos Goddess", was released in The Shining Darkness. It is capable of Summoning Level 5 or higher DARK monsters to the field by discarding a LIGHT monster from the hand. However, the fact that it requires a LIGHT Tuner and two non-Tuner DARK monsters makes it tricky to get out.

Some other notable Chaos monsters are "Phantom of Chaos", which allows you to remove monsters in your Graveyard from play to turn it into an exact duplicate until the end of the turn, and "Chaos Necromancer", which gains 300 ATK for every monster in your Graveyard.

Two other cards, "Chaos End" and "Chaos Greed", are Chaos cards but they do not fit the theme-they both require a sizable amount of your cards to be removed from play and are more useful in a Macro Deck.

A storyline in Yu-Gi-Oh! ZEXAL features "Chaos End Ruler -Ruler of the Beginning and the End-", whose effect is more powerful than any other. This card has not been released unofficially, nor announced, however within ZEXAL it is considered one of the most broken cards ever.

Chaos monsters have also the rare honor of being one of the few cards ever mentioned to be banned in tournament plays due to their rarity and powerful effects, this is also mentioned with other cards such as "Gate Blocker" and "Gate Blocker 2" which had been banned in official turbo duels in Yu-Gi-Oh! 5D's.

Chaos Lockdown (Traditional Format)
While this Deck is dead in every regard due to the banning of "Yata-Garasu" and "Chaos Emperor Dragon - Envoy of the End", it was the most potent Deck in the metagame. It focused on using "Chaos Emperor Dragon" to clear the field and use "Sangan" or "Witch of the Black Forest" to search for "Yata-Garasu", winning the game. At the moment this Deck is only capable of being used in Traditional Format.

Monsters

 * Chaos Emperor Dragon - Envoy of the End (Traditional Format only)
 * Black Luster Soldier - Envoy of the Beginning
 * Chaos Sorcerer
 * Jinzo
 * Yata-Garasu (Traditional Format only)
 * Armageddon Knight
 * Breaker The Magical Warrior
 * Thunder King Rai-Oh
 * Honest
 * Dark Grepher
 * Sangan (Traditional Format only)
 * Witch of the Black Forest (Traditional Format only)
 * Shining Angel
 * Jowgen the Spiritualist (Optional but very useful and deadly)
 * Effect Veiler
 * Spirit Reaper
 * Dark Armed Dragon (Optional, but very useful with Witch of the Black Forest to add it to the hand, due to this card's DEF being only 1000).

Spells

 * Foolish Burial
 * Painful Choice (Traditional Format Only)
 * Monster Reincarnation
 * Giant Trunade (Traditional Format Only)
 * Heavy Storm
 * Cold Wave (Traditional Format Only)
 * Primal Seed
 * Gold Sarcophagus

Traps

 * Bottomless Trap Hole
 * Mirror Force
 * Dark Bribe
 * Sakuretsu Armor
 * Solemn Judgment
 * Tower of Babel
 * Interdimensional Matter Transporter
 * Magic Cylinder

Twilight / Chaos
This focuses on milling the Deck to use "Lightsworn" monsters and Summon "Judgment Dragon" while at the same time placing DARK monsters in the Graveyard in order to Summon "Dark Armed Dragon". Since the milling effect can place vital monsters in the Graveyard, this makes use of Graveyard control cards such as "Monster Reincarnation", "Necro Gardna" and "Pot of Avarice" to make sure that they get the cards required in their hand and Graveyard. With the high amounts of DARK and LIGHT monsters being sent to the Graveyard, "Chaos Sorcerer" can work very well in this Deck. So can "Chaos Necromancer" because you're always dumping cards and the more cards that are in your Graveyard, the more powerful it gets. "Tragoedia" is another important monster for the Deck, offering protection from OTK's, versatility as a Synchro Material and the potential to become a huge beatstick, provided the player has enough cards in their hand.

Monsters

 * Black Luster Soldier - Envoy of the Beginning
 * Dark Armed Dragon
 * Judgment Dragon
 * Chaos Sorcerer
 * Honest
 * Lumina, Lightsworn Summoner
 * Jain, Lightsworn Paladin
 * Garoth, Lightsworn Warrior
 * Lyla, Lightsworn Sorceress
 * Ryko, Lightsworn Hunter
 * Necro Gardna
 * Aurkus, Lightsworn Druid
 * Celestia, Lightsworn Angel
 * Wulf, Lightsworn Beast
 * Plaguespreader Zombie
 * Gorz the Emissary of Darkness
 * Tragoedia
 * Battle Fader
 * Effect Veiler
 * Glow-Up Bulb (Traditional Format Only)
 * Blackwing - Zephyros the Elite
 * Card Trooper
 * Thunder King Rai-Oh
 * Tour Guide From the Underworld

Spells

 * Charge of the Light Brigade
 * Solar Recharge
 * Gold Sarcophagus
 * Monster Reincarnation
 * Allure of Darkness
 * Pot of Avarice
 * Monster Reborn

Traps

 * Royal Decree
 * Beckoning Light
 * Imperial Order(Traditional Format only)
 * Fiend Comedian

Chaos Counter
Counter Fairies can be quite potent when combined with the DARK Counter Trap support and "Black Luster Soldier - Envoy of the Beginning" and "Chaos Sorcerer" are quite easy to Summon as a result of the discarding.

Monsters
Extra Deck:
 * Dark Voltanis
 * Van'Dalgyon the Dark Dragon Lord
 * Bountiful Artemis
 * Layard the Liberator
 * Effect Veiler
 * D.D. Crow
 * Chaos Sorcerer
 * Dimensional Alchemist
 * Herald of Orange Light
 * Sangan (Traditional Format only)
 * Mask of Darkness
 * Harvest Angel of Wisdom
 * Genex Ally Reliever
 * Tragoedia
 * Gorz the Emissary of Darkness
 * Black Luster Soldier - Envoy of the Beginning
 * Stardust Dragon
 * Black Rose Dragon
 * Brionac, Dragon of the Ice Barrier(Traditional Format only)
 * Ally of Justice Catastor
 * Ancient Sacred Wyvern

Spells

 * Trade-In
 * Allure of Darkness
 * Cards from the Sky

Traps

 * Destruction Jammer
 * Seven Tools of the Bandit
 * Debunk
 * Divine Wrath
 * Chivalry
 * Dark Bribe
 * Dark Illusion

Chaos Synchro Deck
If synchro summoning is something you would like to do to special summon powerful Light and Dark monsters, well here's the list for you.

Monsters

 * Black Luster Soldier - Envoy of the Beginning
 * Blackwing - Gale the Whirlwind
 * Chaos Sorcerer
 * Cyber Dragon
 * D.D. Warrior Lady
 * Dark Armed Dragon
 * Gorz the Emissary of Darkness
 * Krebons
 * Marshmallon
 * Morphing Jar
 * Mystic Tomato
 * Plaguespreader Zombie
 * Road Synchron
 * Sangan
 * Spirit Reaper
 * Summoner Monk

Spells

 * Allure of Darkness
 * Burial from a Different Dimension
 * Emergency Teleport
 * Primal Seed

Traps

 * Bottomless Trap Hole
 * Dark Bribe
 * Torrential Tribute

Synchro monsters
Any LIGHT and DARK synchro monsters would be just fine.

Anti-Meta Chaos
See: Chaotic Anti-Meta