Keyword: Mill

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

: Each player mills a card.

, : Target player mills two cards.

+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.

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

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

Whenever a creature attacks you or a planeswalker you control, that creature’s controller mills two cards.

Join forces — Starting with you, each player may pay any amount of mana. Each player mills X cards, where X is the total amount of mana paid this way.

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

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

Flying
Whenever another creature leaves the battlefield, you may have target player mill two cards.
Unearth (: 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.)

As Sewer Nemesis enters the battlefield, choose a player.
Sewer Nemesis’s power and toughness are each equal to the number of cards in the chosen player’s graveyard.
Whenever the chosen player casts a spell, that player mills a card.

You may reveal this card from your opening hand. If you do, at the beginning of the first upkeep, each opponent mills seven cards.
Flying
When Chancellor of the Spires enters the battlefield, you may cast target instant or sorcery card from an opponent’s graveyard without paying its mana cost.

Whenever an opponent loses life, that player mills that many cards. (Damage dealt by sources without infect causes loss of life.)

Shriekhorn enters the battlefield with three charge counters on it.
, Remove a charge counter from Shriekhorn: Target player mills two cards.

, : Target opponent loses 2 life, gets a poison counter, then mills six cards.

Target player discards a card, then mills a card.

Target player mills five cards.

Target player mills half their library, rounded down.

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

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

Return up to three target land cards from your graveyard to your hand.
Dredge 3 (If you would draw a card, you may mill three cards instead. If you do, return this card from your graveyard to your hand.)

When Golgari Thug dies, put target creature card from your graveyard on top of your library.
Dredge 4 (If you would draw a card, you may mill four cards instead. If you do, return this card from your graveyard to your hand.)

Golgari Grave-Troll enters the battlefield with a +1/+1 counter on it for each creature card in your graveyard.
, Remove a +1/+1 counter from Golgari Grave-Troll: Regenerate Golgari Grave-Troll.
Dredge 6 (If you would draw a card, you may mill six cards instead. If you do, return this card from your graveyard to your hand.)

Sacrifice Shambling Shell: Put a +1/+1 counter on target creature.
Dredge 3 (If you would draw a card, you may mill three cards instead. If you do, return this card from your graveyard to your hand.)