Aven Reedstalker

Soul Read

Choose one —
• Counter target spell unless its controller pays {4}.
• Draw two cards.

Brineborn Cutthroat

Flash (You may cast this spell any time you could cast an instant.)
Whenever you cast a spell during an opponent's turn, put a +1/+1 counter on this creature.

Wavebreak Hippocamp

Whenever you cast your first spell during each opponent's turn, draw a card.

Stinging Lionfish

Whenever you cast your first spell during each opponent's turn, you may tap or untap target nonland permanent.

Fading Hope

Return target creature to its owner's hand. If its mana value was 3 or less, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Starlight Snare

Enchant creature
When Starlight Snare enters, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Vexing Gull

Island

Thriving Isle

Thriving Isle enters tapped. As it enters, choose a color other than blue.
{T}: Add {U} or one mana of the chosen color.

Wind Strider

Flash (You may cast this spell any time you could cast an instant.)
Flying

Venser, Shaper Savant

Flash (You may cast this spell any time you could cast an instant.)
When Venser, Shaper Savant enters, return target spell or permanent to its owner's hand.

Uncomfortable Chill

Creatures your opponents control get -2/-0 until end of turn.
Draw a card.

Spectral Sailor

Flash (You may cast this spell any time you could cast an instant.)
Flying
{3}{U}: Draw a card.