Mountain

Nivix Cyclops

Defender
Whenever you cast an instant or sorcery spell, this creature gets +3/+0 until end of turn and can attack this turn as though it didn't have defender.

Mana Leak

Counter target spell unless its controller pays {3}.

Zephyr Scribe

{U}, {T}: Draw a card, then discard a card.
Whenever you cast a noncreature spell, untap this creature.

Negate

Elusive Spellfist

Whenever you cast a noncreature spell, this creature gets +1/+0 until end of turn and can't be blocked this turn.

Spellheart Chimera

Flying, trample
Spellheart Chimera's power is equal to the number of instant and sorcery cards in your graveyard.

Island

Lightning Bolt

Lightning Bolt deals 3 damage to any target.

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.)

Lofty Denial

Counter target spell unless its controller pays {1}. If you control a creature with flying, counter that spell unless its controller pays {4} instead.

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.

Dance of the Skywise

Until end of turn, target creature you control becomes a blue Dragon Illusion with base power and toughness 4/4, loses all abilities, and gains flying.