Dreamborn Muse

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

Hedron Crab

Landfall — Whenever a land you control enters, target player mills three cards.

Mind Sculpt

Island

Arcane Laboratory

Each player can't cast more than one spell each turn.

Ulamog, the Infinite Gyre

When you cast this spell, destroy target permanent.
Indestructible
Annihilator 4 (Whenever this creature attacks, defending player sacrifices four permanents of their choice.)
When Ulamog, the Infinite Gyre is put into a graveyard from anywhere, its owner shuffles their graveyard into their library.

Memory Erosion

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

Undead Alchemist

If a Zombie you control would deal combat damage to a player, instead that player mills that many cards.
Whenever a creature card is put into an opponent's graveyard from their library, exile that card and create a 2/2 black Zombie creature token.

Counterspell

Wash Out

Return all permanents of the color of your choice to their owners' hands.

Mana Leak

Counter target spell unless its controller pays {3}.

Isochron Scepter

Imprint — When Isochron Scepter enters, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Negate

Mesmeric Orb

Whenever a permanent becomes untapped, that permanent's controller mills a card.