Song of Stupefaction

Enchant creature or Vehicle
When Song of Stupefaction enters, you may mill two cards. (You may put the top two cards of your library into your graveyard.)
Fathomless descent — Enchanted permanent gets -X/-0, where X is the number of permanent cards in your graveyard.

Tome Scour

Rotcrown Ghoul

When Rotcrown Ghoul dies, target player mills five cards.

Drowner Initiate

Whenever a player casts a blue spell, you may pay {1}. If you do, target player mills two cards.

Winds of Rebuke

Return target nonland permanent to its owner's hand. Each player mills two cards.

Venture Deeper

Target player mills four cards. (Then exile this card. You may cast the creature later from exile.)

Merfolk Secretkeeper

Merfolk Secretkeeper // Venture Deeper

Ghoulcaller's Bell

Vedalken Entrancer

Thassa's Bounty

Draw three cards. Target player mills three cards.

Excavated Wall

Defender
{1}, {T}: Mill a card. (Put the top card of your library into your graveyard.)

Armored Skaab

When Armored Skaab enters, mill four cards.

Fear of Death

Enchant creature
When Fear of Death enters, mill two cards. (Put the top two cards of your library into your graveyard.)
Enchanted creature gets -X/-0, where X is the number of cards in your graveyard.

Thought Scour

Target player mills two cards.
Draw a card.

Merfolk Mesmerist

Curse of the Bloody Tome

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

Vision Charm

Choose one —
• Target player mills four cards.
• Choose a land type and a basic land type. Each land of the first chosen type becomes the second chosen type until end of turn.
• Target artifact phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before its controller untaps during their next untap step.)

Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Shard of Broken Glass

Equipped creature gets +1/+0.
Whenever equipped creature attacks, you may mill two cards.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Mental Note

Deranged Assistant

{T}, Mill a card: Add {C}. (To mill a card, put the top card of your library into your graveyard.)

Disturbing Conversion

Flash
Enchant creature
When Disturbing Conversion enters, each player mills two cards.
Enchanted creature gets -X/-0, where X is the number of cards in its controller's graveyard.

Laboratory Brute

When Laboratory Brute enters, mill four cards.

Chronic Flooding

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

Sage's Row Denizen

Whenever another blue creature you control enters, target player mills two cards.

Merrow Witsniper

When Merrow Witsniper enters, target player mills a card.

Dreadwaters

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

Laboratory Maniac

If you would draw a card while your library has no cards in it, you win the game instead.

Jace's Erasure

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

Vessel of Paramnesia

{U}, Sacrifice Vessel of Paramnesia: Target player mills three cards. Draw a card.

Selhoff Occultist

Whenever Selhoff Occultist or another creature dies, target player mills a card.

Dampen Thought

Target player mills four cards.
Splice onto Arcane {1}{U} (As you cast an Arcane spell, you may reveal this card from your hand and pay its splice cost. If you do, add this card's effects to that spell.)

Towering-Wave Mystic

Whenever Towering-Wave Mystic deals damage, target player mills that many cards.

Compelling Argument

Target player mills five cards.
Cycling {U} ({U}, Discard this card: Draw a card.)

Thassa's Devourer

Constellation — Whenever Thassa's Devourer or another enchantment you control enters, target player mills two cards.

Evanescent Intellect

Enchant creature
Enchanted creature has "{1}{U}, {T}: Target player mills three cards."

Sultai Skullkeeper

When Sultai Skullkeeper enters, mill two cards.

Homarid Explorer

When Homarid Explorer enters, target player mills four cards.

Dream Twist

Target player mills three cards.
Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Seer of the Last Tomorrow

{U}, {T}, Discard a card: Target player mills three cards.

Drownyard Amalgam

When Drownyard Amalgam enters, target player mills three cards. (They put the top three cards of their library into their graveyard.)
{2}{U}: Drownyard Amalgam can't be blocked this turn.

Cathartic Adept

Island

Thought Collapse

Counter target spell. Its controller mills three cards.

Halo-Charged Skaab

When Halo-Charged Skaab enters, each player mills two cards. Then you may put an instant, sorcery, or battle card from your graveyard on top of your library. (To mill two cards, a player puts the top two cards of their library into their graveyard.)

Fallaji Archaeologist

When Fallaji Archaeologist enters, mill three cards. You may put a noncreature, nonland card from among the cards milled this way into your hand. If you don't, put a +1/+1 counter on Fallaji Archaeologist. (To mill a card, put the top card of your library into your graveyard.)