Countermand

Counter target spell. Its controller mills four cards.

Countersquall

Counter target noncreature spell. Its controller loses 2 life.

Counterspell

Kynaios and Tiro of Meletis

At the beginning of your end step, draw a card. Each player may put a land card from their hand onto the battlefield, then each opponent who didn't draws a card.

Countervailing Winds

Counter target spell unless its controller pays {1} for each card in your graveyard.
Cycling {2} ({2}, Discard this card: Draw a card.)

Counterlash

Counter target spell. You may cast a spell that shares a card type with it from your hand without paying its mana cost.

Mana Leak

Counter target spell unless its controller pays {3}.

Negate

Trostani, Selesnya's Voice

Whenever another creature you control enters, you gain life equal to that creature's toughness.
{1}{G}{W}, {T}: Populate. (Create a token that's a copy of a creature token you control.)

Flash Counter

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.