Mill Deck

A Mill Deck (デッキ破壊 Dekki Hakai, Deck Destruction) centers around getting through the contents of your opponent's Deck very rapidly, usually resulting in a Deck Out.

Origin
The name "Mill Deck" comes from Millstone, a card in the first widely-popular TCG, Magic the Gathering. Millstone allows the user to put two cards from the top of one player's deck (or, "library" in Magic), into their graveyard; there are dozens of other cards like this in Magic, but because Millstone was the first, the act of putting cards from the deck into the discard pile directly became known as "Milling." Decks that centered around the alternate win-condition of depleting one's opponents' decks of cards became known as "Mill Decks," a term that has since spread to most other card games with this win condition.

Typical Cards Used
It is best to either mill through your opponent's deck quickly, have more cards in your deck than your opponent does, or fill your deck up with cards like Pot of Avarice or The Transmigration Prophecy.
 * "A/D Changer"
 * "Book of Eclipse"
 * "Book of Moon"
 * "Book of Taiyou"
 * "Burial from a Different Dimension" (Combined With A/D Changer)
 * "Assault on GHQ"
 * "The Bistro Butcher"
 * "Chainsaw Insect"
 * "Card Destruction" (Which can be vicious when combined with "Serial Spell") (This card is also deadly with "Giant Trunade")
 * "Cyber Jar" Traditional Format Only
 * "Dark Diviner"
 * "DNA Checkup"
 * "Dragged Down into the Grave"
 * "Gravekeeper's Servant" (vicious with multiple copies on the field and with "Savage Colosseum" or "Final Attack Orders" active)
 * "Hand Destruction"
 * "Hiro's Shadow Scout"
 * Most "Iron Chain" monsters or cards
 * "Level Modulation" (forces opponent to draw 2 cards while leaving you defence)
 * "Morphing Jar" limited (which may be vicious when combined with Book of Eclipse)
 * "Morphing Jar #2"
 * "Needle Worm"
 * "Greed"
 * "Necroface"
 * "Inferno Tempest" (which will mill more cards if "Necroface" is in either player's deck or Graveyard)
 * "Goblin Zombie"
 * "Robbin' Zombie"
 * "Destiny Hero - Defender"
 * "Vampire Lady"
 * "Vampire Lord"
 * "Neo-Spacian Glow Moss"
 * "Kuraz the Light Monarch"
 * "Warm Worm"
 * "Dark Bribe"
 * "Don Zaloog"
 * "Bicorn Re'em"
 * "Voltic Bicorn"
 * "Dark World Dealings" (though it might combo pretty well with Serial Spell, but you might as well just use 2 hand destructions)

"Gravekeeper's Servant", "Don Zaloog", "Assault on GHQ", "Sasuke Samurai #3", "Cup of Ace", etc, are also helpful. "Destiny Hero - Defender" makes your opponent draw a card during their Standby Phase while offering the highest DEF for a Level 4 monster. "Chainsaw Insect" is an offensive counterpart to "Destiny Hero - Defender", with 2400 ATK at Level 4. "Night Assailant" can also help you bring back "Needle Worm", "Morphing Jar", and "Morphing Jar #2". "Desertapir" can also help reuse "Needle Worm" or similar cards, and "Soul Reversal" can be used for a similar purpose. "The Shallow Grave" is also helpful for re-using Flip Effect Monsters, also "Dark Bribe" can be very useful, it negates 1 your opponent's spell or trap card and let's them draw an extra card. "Book of Eclipse" is also very good in stopping a swarm of monsters from attacking you while at the same time putting all monsters including your own into face down defense position, then at the end phase your opponent must flip all their face down monsters face up while drawing a card for each one flipped face up in this manner. This also a very good way to counter-act "Red Dragon Archfiend" when destroying all defense position monsters for the fact it puts all you opponent's monsters into defense position as well to feel the effect. Also, even though "Kuraz the Light Monarch" may be out of place among level four or less flip effect monsters, he will allow you to destroy two cards on the field and make your opponent draw two cards.

''Gokipon' can be useful in a mill deck since it allows you to search out Needle Worm or Warm Worm.

The "Iron Chain" cards in Crossroads of Chaos also aid this purpose. Another useful card from the OCG released in the TCG Crossroads of Chaos is the Virus Cannon.

When "Necroface" is removed from play, it removes five cards off both player's deck. You can make a deadly combo by having summoning Necroface while "Future Visions" is on the field.

Another strategy is to have 3 "Soul-Absorbing Bone Towers" in play (most likely summoned with "Inferno Reckless Summon"), then suicide a "Pyramid Turtle" to Special Summon another "Pyramid Turtle" (This combo will mill out 6 cards at a time), then repeat the step until you're at your last one, which you should summon a monster that can revive one of the "Turtles" like "Zombie Master", and then activate "The Transmigration Prophecy" or "Pot of Avarice" to return the other ones (at least 2) in the Graveyard back to your deck. Afterwards, you could use "Zombie Master" to Special Summon 1 of the "Turtles" and repeat, if this method is repeated it is possible to end the duel in one turn (One Turn Mill). It is optional to have a "Spirit Barrier" or a 4 countered "Clock Tower Prison" in place to protect your life points.

There's even a combo that might force your opponent to Mill their Deck every time they attack. Use "Vampire's Curse" in Defense Position, "Soul-Absorbing Bone Tower". Every time your opponent destroys "Vampire's Curse", Special Summon it in Defense Position, allowing you to draw a card and discard two cards from your opponent's Deck. That'll lock your opponent into a never ending Mill. (Mill Lockdown)

The most effective mill deck is "Empty Jar".

Morphing Jar Mill Deck
See also "Empty Jar"

This deck consists of using "Morphing Jar"'s effect and getting cards to recycle itself.

Use "Spear Cretin"" and "The Shallow Grave",to revive "Morphing Jar" face down. "Book of Eclipse", "Book of Moon" and "Book of Taiyou" also works well in this deck. "Magical Stone Excavation", "Card Destruction", "Soul Reversal", "Giant Rat" and "Sangan" works well, too.

Giving control of "Morphing Jar" to your opponent with cards such as "Shien's Spy", "Bone Temple Block", "Give and Take", "Creature Swap" and others makes flipping "Morphing Jar" simpler with cards like "Swords of Revealing Light" and "Swords of Concealing Light". However, keep in mind that adding trap cards will make the deck much slower. Over a long duel, "Gravekeeper's Servant" will prove useful and set in pressure on your opponent when their deck is down to around 8 cards.

Weaknesses
Decks that require milling will love the fact that you are rifling through their cards. "Lightsworns" are the biggest threat to mill decks. If you have a deck that sends cards from your opponent's deck to the graveyard, that will just put more monsters in there ready for "Judgment Dragon". If your deck is a Draw Mill, it will result in getting a higher chance of "Judgment Dragon" or any other "Lightsworns" that may appear. Notably, "Ehren, Lightsworn Monk" will return your face-down "Morphing Jar" to the deck without his effect applying. Some "B.E.S." decks have milling capabilities, but are not as strong as "Lightsworns".

"Removed from play" decks are a nasty threat too, especially decks that revolve around the effect of "Helios - The Primordial Sun", "Helios Duo Megistus" and "Helios Trice Megistus". It doesn't really matter whose Graveyard the monsters/other cards are getting removed, either way it will end badly for a mill deck. If it revolves around removing from play your cards, your mills will be negated, your "Morphing Jar" won't be flipped and any backup solutions will probably be dealt with. If it revolves around removing from play their cards, then getting cards into the graveyard will be a breeze for them.

"Volcanic" decks are a minor threat, as they can't or won't attack your face-downs, they inflict decent damage over time and like "Volcanic Scattershot" can be a threat if milled. These decks usually end up getting Hand Advantage because, (on average) little to no cards are used per turn. Beware of cards like "Solar Flare Dragon" and "Volcanic Slicer" that inflict damage over time. "Volcanic Doomfire" is something to worry about. 3000 ATK means that (considering the current Metagame) it is not easily destroyed. Its' other effect will do a nice burn to you and take out a lot of your face-downs without them being flipped. Keep "Lightning Vortex" side decked.

"Dark Simorgh" is not a deck, but a card to be careful of. Preventing you to Set cards is not good at all and "Dark Simorgh" can be easily summoned, too. With this card in play, you won't be able to set cards like "Morphing Jar", "Needle Worm", "Destiny Hero - Defender", "Hiro's Shadow Scout" and "Warm Worm". Bear in mind, though, that you can still use "Book of Moon" to re-set these kind of cards. Also, use "Book of Eclipse" to solve both problems for a little while. You can then Set cards while "Dark Simorgh" is face-down. Even better, use "Swords of Concealing Light" to give a longer-lasting stall. Most importantly, beware its' ATK (2700) and the fact that it can be summoned from the Hand or the Graveyard. Use its' low DEF to your advantage and serve with "Macro Cosmos".

Zombiefrog Mill OTK
This strategy is based into the effect of "Substitoad" (although currently banned) to Special Summon "Frogs" from your Deck continuously and Mill your opponent in just one turn. Due to the banning of Substitoad, this strategy was eradicated. Step by step, this is how it works: You should Special Summon "Substitoad", preferably with "One for One", and Normal Summon a "Frog". Activate "DNA Surgery" or "Zombie World" to change all your Frogs to Zombie. Make sure you have Summoned "Soul-Absorbing Bone Tower" in this turn. Tribute and Special Summon "Frogs" continuously; "Soul-Absorbing Bone Tower" will Mill your opponent whilst doing that. Up to 14 "Frogs" may be Special Summoned for you to win.