Grindstone

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

Flitting Guerrilla

Flying
When this creature dies, each player mills two cards. Then you may exile this card. When you do, put target creature 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.)

Grindclock

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

Desperate Bloodseeker

Lifelink
When this creature enters, target player mills two cards. (They put the top two cards of their library into their graveyard.)

Flint Golem

Whenever this creature becomes blocked, defending player mills three cards.

Hair-Strung Koto

Tap an untapped creature you control: Target player mills a card.

Gnawing Vermin

When this creature enters, target player mills two cards.
When this creature dies, target creature you don't control gets -1/-1 until end of turn.

Extractor Demon

Flying
Whenever another creature leaves the battlefield, you may have target player mill two cards.
Unearth {2}{B} ({2}{B}: 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.)

Ghoulcaller's Bell

Eye Collector

Flying
Whenever this creature deals combat damage to a player, each player mills a card. (Each player puts the top card of their library into their graveyard.)

Breach the Multiverse

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

Codex Shredder

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

Dread Summons

Each player mills X cards. For each creature card put into a graveyard this way, you create a tapped 2/2 black Zombie creature token. (To mill a card, a player puts the top card of their library into their graveyard.)