Counterspell

Fatal Push

Destroy target creature if it has mana value 2 or less.
Revolt — Destroy that creature if it has mana value 4 or less instead if a permanent you controlled left the battlefield this turn.

Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Snow-Covered Swamp

Iceberg Cancrix

Whenever another snow permanent you control enters, you may have target player mill two cards.

Thought Scour

Target player mills two cards.
Draw a card.

Traumatize

Target player mills half their library, rounded down.

Drowned Secrets

Whenever you cast a blue spell, target player mills two cards.

Ice Tunnel

({T}: Add {U} or {B}.)
Ice Tunnel enters tapped.