Pact of Negation

Counter target spell.
At the beginning of your next upkeep, pay {3}{U}{U}. If you don't, you lose the game.

Syncopate

Counter target spell unless its controller pays {X}. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.

Baral, Chief of Compliance

Instant and sorcery spells you cast cost {1} less to cast.
Whenever a spell or ability you control counters a spell, you may draw a card. If you do, discard a card.

Stern Scolding

Counter target creature spell with power or toughness 2 or less.

Island

Phantom Interference

Spree (Choose one or more additional costs.)
+ {3} — Create a 2/2 white Spirit creature token with flying.
+ {1} — Counter target spell unless its controller pays {2}.

Siren Stormtamer

Flying
{U}, Sacrifice this creature: Counter target spell or ability that targets you or a creature you control.

Aetherize

Return all attacking creatures to their owner's hand.

Overcharged Amalgam

Flash
Flying
Exploit (When this creature enters, you may sacrifice a creature.)
When this creature exploits a creature, counter target spell, activated ability, or triggered ability.

Spell Pierce

Counter target noncreature spell unless its controller pays {2}.

Condescend

Counter target spell unless its controller pays {X}. Scry 2. (Look at the top two cards of your library, then put any number of them on the bottom and the rest on top in any order.)

Reasonable Doubt

Counter target spell unless its controller pays {2}.
Suspect up to one target creature. (A suspected creature has menace and can't block.)

Summary Dismissal

Exile all other spells and counter all abilities.

Counterspell

Wash Away

Cleave {1}{U}{U} (You may cast this spell for its cleave cost. If you do, remove the words in square brackets.)
Counter target spell [that wasn't cast from its owner's hand].

Dissolve

Counter target spell. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)