Mill

Mill is an informal term used in the game describing cards moving out of a player's library to somewhere even less useful (meaning: anywhere other than the hand).

The term refers to the card, Millstone, which was the first to feature the mechanic. "Milling" is a strategy some decks use which take advantage of the decking rule:

From the ()

Presumably, emptying your opponent's library is one way to ensure a game loss, though you have to wait for your opponent to actually draw a card, a fine point to the rule.

List of mill instants and sorceries

Instants

• Archive Trap — target opponent (thirteen) - Trap
• Brain Freeze — target player (three) - Storm
• Broken Ambitions — counter target spell unless its controller pays . Clash with an opponent. If you win, that spell's controller (four)
• Dampen Thought — target player (four) - Splice onto Arcane
• Dream Twist — target player (three) - Flashback
• Induce Paranoia — counter target spell. If was spent to cast Induce Paranoia, that spell's controller (X), where X is the spell's converted mana cost.
• Lammastide Weave — name a card, then target player (one). If that card is the named card, you gain life equal to its converted mana cost.
• Psychic Spiral — shuffle all cards from your graveyard into your library, then target player (that many cards)
• Ray of Erasure — target player (one) - Slowtrip
• Thought Scour — target player (two) - Cantrip
• Vision Charm — target player (four) - tri-modal spell

Sorceries

• Chill of Foreboding — each player (five) - Flashback
• Destroy the Evidence — destroy target land. Its controller reveals cards from the top of his or her library until he or she reveals a land card, mill those cards
• Dreadwaters — target player (X), where X is the number of lands you control.
• Glimpse the Unthinkable — target player (ten)
• Horrifying Revelation — target player (one) - also discards a card
• Increasing Confusion — target player (X) - If Increasing Confusion was cast from a graveyard, twice (X) instead. - Flashback
• Memory Sluice — Template:Ub target player (four) - Conspire
• Mind Sculpt — target opponent (seven)
• Psychic Drain — target player (X) and you gain X life
• Sanity Grinding — Chroma - Reveal the top ten cards of your library. For each blue mana symbol in the mana costs of the revealed cards, target opponent (one). Then put the cards you revealed this way on the bottom of your library in any order.
• Shared Trauma — Join forces - Starting with you, each player may pay any amount of mana. Each player (X), where X is the total amount of mana paid this way.
• Tome Scour — target player (five)
• Traumatize — target player (half of library, rounded down)

Creatures which cause mill

• Ambassador Laquatus — - : target player (three)
• Cathartic Adept — - : target player (one)
• Chancellor of the Spires — you may reveal this card from your opening hand. If you do, at the beginning of the first upkeep, each opponent (seven)
• Crosstown Courier — - whenever Crosstown Courier deals combat damage to a player, that player (that many cards)
• Doorkeeper — - , : target player (X), where X is the number of creatures with defender you control.
• Dreamborn Muse — at the beginning of each player's upkeep, that player (X), where X is the number of cards in his or her hand.
• Drowner Initiate — whenever a player casts a blue spell, you may pay . If you do, target player (two)
• Drowner of Secrets — tap an untapped Merfolk you control: target player (one)
• Enigma Eidolon — - , sacrifice Enigma Eidolon: target player (three)
• Geralf's Mindcrusher — when Geralf's Mindcrusher enters the battlefield, target player (five) - Undying
• Geth, Lord of the Vault — - : put target artifact or creature card with converted mana cost X from an opponent's graveyard onto the battlefield under your control tapped. Then that player (X).
• Halimar Excavator — whenever Halimar Excavator or another Ally enters the battlefield under your control, target player (X), where X is the number of Allies you control.
• Hedron Crab — Landfall - Whenever a land enters the battlefield under your control, target player (three)
• Ink Dissolver — Kinship - at the beginning of your upkeep, you may look at the top card of your library. If it shares a creature type with Ink Dissolver, you may reveal it. If you do, each opponent (three).
• Lich Lord of Unx — - : target player loses X life and (X), where X is the number of Zombies you control.
• Merfolk Mesmerist — - , : target player (two)
• Merrow Witsniper — when Merrow Witsniper enters the battlefield, target player (one)
• Mindshrieker — - : target player (one); Mindshrieker gets +X/+X until end of turn, where X is that card's converted mana cost.
• Nemesis of Reason — whenever Nemesis of Reason attacks, defending player (ten)
• Reef Pirates — whenever Reef Pirates deals damage to an opponent, that player (one)
• Riddlekeeper — whenever a creature attacks you or a planeswalker you control, that creature's controller (two)
• Rotcrown Ghoul — when Rotcrown Ghoul dies, target player (five)
• Screeching Silcaw — Metalcraft - Whenever Screeching Silcaw deals combat damage to a player, if you control three or more artifacts, that player (four)
• Screeching Sliver — all Slivers have ": target player (one)"
• Selhoff Occultist — whenever Selhoff Occultist or another creature dies, target player (one)
• Sewer Nemesis — as Sewer Nemesis enters the battlefield, choose a player. Whenever the chosen player casts a spell, that player (one)
• Shriekgeist — whenever Shriekgeist deals combat damage to a player, that player (two)
• Soratami Mindsweeper — - , return a land you control to its owner's hand: target player (two)
• Stern Mentor — - Soulbond - paired with another creature, each of those creatures has ": target player (two)"
• Vedalken Entrancer — - , : target player (two)

Planeswalkers which cause mill

• Jace Beleren — -10: target player (twenty)
• Jace, Memory Adept — +1: Draw a card. Target player (one); 0: target player (ten)

Enchantments

• Chronic Flooding — enchant land - whenever enchanted land becomes tapped, its controller (three)
• Curse of the Bloody Tome — enchant player - at the beginning of enchanted player's upkeep, that player (two)
• Infernal Genesis — at the beginning of each player's upkeep, that player (one). Then that player puts X 1/1 black Minion creature tokens onto the battlefield, where X is that card's converted mana cost.
• Memory Erosion — whenever an opponent casts a spell, that player (two)
• Jace's Erasure — whenever you draw a card, you may have target player (one)

Artifacts which cause mill

• Codex Shredder — - : target player (one)
• Decimator Web — - , : target opponent loses 2 life, gets a poison counter, then (six)
• Ghoulcaller's Bell — - : each player (one)
• Grindclock — - : put a charge counter on Grindclock. : Target player (X), where X is the number of charge counters on Grindclock.
• Grinding Station — - , sacrifice an artifact: target player (three)
• Hair-Strung Koto — tap an untapped creature you control: target player (one)
• Keening Stone — - , : target player (X), where X is the number of cards in that player's graveyard.
• Mesmeric Orb — whenever a permanent becomes untapped, that permanent's controller (one)
• Millstone — - , : target player (two)
• Sands of Delirium — - , : target player (X)
• Shriekhorn — Shriekhorn enters the battlefield with three charge counters on it. , remove a charge counter from Shriekhorn: target player (two)
• Sword of Body and Mind — Equipment - whenever equipped creature deals combat damage to a player, you put a 2/2 green Wolf creature token onto the battlefield and that player (ten)
• Tower of Murmurs — - , : target player (eight)
• Whetstone — - : each player (two)
• Whetwheel — - , : target player (X) - Morph
• Worry Beads — at the beginning of each player's upkeep, that player (one)

Lands which cause mill

• Duskmantle, House of Shadow — - , : target player (one)
• Nephalia Drownyard — - , : target player (three)

Notes

In the above list; (number) means puts the top (number) card(s) of his or her library into his or her graveyard.