Dreadwaters

Target player mills X cards, where X is the number of lands you control.

Aetherize

Return all attacking creatures to their owner's hand.

Fleet Swallower

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Fog Bank

Defender (This creature can't attack.)
Flying
Prevent all combat damage that would be dealt to and dealt by this creature.

Psychic Corrosion

Whenever you draw a card, each opponent mills two cards.

Sphinx's Tutelage

Whenever you draw a card, target opponent mills two cards. If two nonland cards that share a color were milled this way, repeat this process.
{5}{U}: Draw a card, then discard a card.

Jace's Erasure

Whenever you draw a card, you may have target player mill a card.

Thought Collapse

Counter target spell. Its controller mills three cards.

Psychic Spiral

Shuffle all cards from your graveyard into your library. Target player mills that many cards.

Island

Sorcerous Squall

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Target opponent mills nine cards, then you may cast an instant or sorcery spell from that player's graveyard without paying its mana cost. If that spell would be put into a graveyard, exile it instead.

Omniscience

You may cast spells from your hand without paying their mana costs.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Mind Sculpt

Undead Alchemist

If a Zombie you control would deal combat damage to a player, instead that player mills that many cards.
Whenever a creature card is put into an opponent's graveyard from their library, exile that card and create a 2/2 black Zombie creature token.

Wall of Lost Thoughts

Defender (This creature can't attack.)
When Wall of Lost Thoughts enters, target player mills four cards. (They put the top four cards of their library into their graveyard.)

Cancel

Irenicus's Vile Duplication

Create a token that's a copy of target creature you control, except the token has flying and it isn't legendary.

Helm of the Host

At the beginning of combat on your turn, create a token that's a copy of equipped creature, except the token isn't legendary. That token gains haste.
Equip {5}

Keening Stone

{5}, {T}: Target player mills X cards, where X is the number of cards in that player's graveyard.

Cut Your Losses

Casualty 2 (As you cast this spell, you may sacrifice a creature with power 2 or greater. When you do, copy this spell and you may choose a new target for the copy.)
Target player mills half their library, rounded down.

Bruvac the Grandiloquent

If an opponent would mill one or more cards, they mill twice that many cards instead. (To mill a card, a player puts the top card of their library into their graveyard.)

Archive Trap

If an opponent searched their library this turn, you may pay {0} rather than pay this spell's mana cost.
Target opponent mills thirteen cards.

Solve the Equation

Search your library for an instant or sorcery card, reveal it, put it into your hand, then shuffle.

Grindstone

{3}, {T}: Target player mills two cards. If two cards that share a color were milled this way, repeat this process.

Traumatize

Target player mills half their library, rounded down.

Didn't Say Please

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Counterspell

Curse of the Bloody Tome

Enchant player
At the beginning of enchanted player's upkeep, that player mills two cards.

Belltower Sphinx

Flying
Whenever a source deals damage to Belltower Sphinx, that source's controller mills that many cards.

Dramatic Reversal

Untap all nonland permanents you control.

Codex Shredder

{T}: Target player mills a card. (They put the top card of their library into their graveyard.)
{5}, {T}, Sacrifice Codex Shredder: Return target card from your graveyard to your hand.

Negate

Eaten by Piranhas

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
Enchanted creature loses all abilities and is a black Skeleton creature with base power and toughness 1/1. (It loses all other colors, card types, and creature types.)

Dreamborn Muse

At the beginning of each player's upkeep, that player mills X cards, where X is the number of cards in their hand.

Winter Moon

Players can't untap more than one nonbasic land during their untap steps.

Evacuation

Return all creatures to their owners' hands.

Jace, Memory Adept

+1: Draw a card. Target player mills a card.
0: Target player mills ten cards.
−7: Any number of target players each draw twenty cards.

Shadow Kin

Flash
At the beginning of your upkeep, each player mills three cards. You may exile a creature card from among the cards milled this way. If you do, Shadow Kin becomes a copy of that card, except it has this ability.

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Sands of Delirium

Deepmuck Desperado

Whenever you commit a crime, each opponent mills three cards. This ability triggers only once each turn. (Targeting opponents, anything they control, and/or cards in their graveyards is a crime.)

Tome Scour

Jace, Wielder of Mysteries

If you would draw a card while your library has no cards in it, you win the game instead.
+1: Target player mills two cards. Draw a card.
−8: Draw seven cards. Then if your library has no cards in it, you win the game.

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Jace's Phantasm

Flying
Jace's Phantasm gets +4/+4 as long as an opponent has ten or more cards in their graveyard.

Memory Erosion

Whenever an opponent casts a spell, that player mills two cards.

Forced Fruition

Whenever an opponent casts a spell, that player draws seven cards.

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Dissipation Field

Whenever a permanent deals damage to you, return it to its owner's hand.

Millstone

Filter Out

Return all noncreature, nonland permanents to their owners' hands.

Chronic Flooding

Enchant land
Whenever enchanted land becomes tapped, its controller mills three cards.

Thought Scour

Target player mills two cards.
Draw a card.

Disallow

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Maddening Cacophony

Kicker {3}{U}
Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

Fractured Sanity

Each opponent mills fourteen cards.
Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.)
When you cycle Fractured Sanity, each opponent mills four cards.

Zellix, Sanity Flayer

Hive Mind — Whenever a player mills one or more creature cards, you create a 1/1 black Horror creature token.
{1}, {T}: Target player mills three cards.
Choose a Background (You can have a Background as a second commander.)

Countermand

Counter target spell. Its controller mills four cards.

Teferi's Tutelage

When Teferi's Tutelage enters, draw a card, then discard a card.
Whenever you draw a card, target opponent mills two cards. (They put the top two cards of their library into their graveyard.)

Terisian Mindbreaker

Whenever Terisian Mindbreaker attacks, defending player mills half their library, rounded up.
Unearth {1}{U}{U}{U} ({1}{U}{U}{U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

Grindclock

{T}: Put a charge counter on Grindclock.
{T}: Target player mills X cards, where X is the number of charge counters on Grindclock.

Manic Scribe

When Manic Scribe enters, each opponent mills three cards.
Delirium — At the beginning of each opponent's upkeep, if there are four or more card types among cards in your graveyard, that player mills three cards.