Glistener Seer

Glistener Seer enters with three oil counters on it.
{T}, Remove an oil counter from Glistener Seer: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Ghoulcaller's Bell

Screeching Sliver

All Slivers have "{T}: Target player mills a card."

Glacial Grasp

Tap target creature. Its controller mills two cards. That creature doesn't untap during its controller's next untap step. (They put the top two cards of their library into their graveyard.)
Draw a card.

Dreadwaters

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

Selhoff Occultist

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

Reef Pirates

Whenever Reef Pirates deals damage to an opponent, that player mills a card.

Countermand

Counter target spell. Its controller mills four cards.

Cathartic Adept

Merrow Witsniper

When Merrow Witsniper enters, target player mills a card.

Vedalken Entrancer

Grapple with the Past

Mill three cards, then you may return a creature or land card from your graveyard to your hand. (To mill three cards, put the top three cards of your library into your graveyard.)

Thought Collapse

Counter target spell. Its controller mills three cards.

Sage's Row Denizen

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

Rotcrown Ghoul

When Rotcrown Ghoul dies, target player mills five cards.

Didn't Say Please

Broken Ambitions

Counter target spell unless its controller pays {X}. Clash with an opponent. If you win, that spell's controller mills four cards. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Evanescent Intellect

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

Homarid Explorer

When Homarid Explorer enters, target player mills four cards.

Persistent Petitioners

{1}, {T}: Target player mills a card. (They put the top card of their library into their graveyard.)
Tap four untapped Advisors you control: Target player mills twelve cards.
A deck can have any number of cards named Persistent Petitioners.

Redtooth Genealogist

When Redtooth Genealogist enters, create a Royal Role token attached to another target creature you control. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1 and has ward {1}.)

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.)

Curse of the Bloody Tome

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

Merfolk Mesmerist

Pelargir Survivor

{T}: Add one mana of any color. Spend this mana only to cast an instant or sorcery spell.
{5}{U}, {T}: Target player mills three cards. (They put the top three cards of their library into their graveyard.)

Wood Sage

{T}: Choose a creature card name. Reveal the top four cards of your library and put all of them with that name into your hand. Put the rest into your graveyard.

Enigma Eidolon

{U}, Sacrifice Enigma Eidolon: Target player mills three cards.
Whenever you cast a multicolored spell, you may return Enigma Eidolon from your graveyard to your hand.

Chronic Flooding

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

Towering-Wave Mystic

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