Milling

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.)

Wall of Lost Thoughts

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

Island

Capture Sphere

Flash (You may cast this spell any time you could cast an instant.)
Enchant creature
When this Aura enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Vedalken Entrancer

Belltower Sphinx

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

Reckless Scholar

{T}: Target player draws a card, then discards a card.

Thought Collapse

Counter target spell. Its controller mills three cards.

Towering-Wave Mystic

Whenever this creature deals damage, target player mills that many cards.

Sweep Away

Return target creature to its owner's hand. If that creature is attacking, you may put it on top of its owner's library instead.

Thought Scour

Target player mills two cards.
Draw a card.

Thriving Isle

This land enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Teferi's Tutelage

When this enchantment 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.)