Agent of Treachery

When Agent of Treachery enters, gain control of target permanent.
At the beginning of your end step, if you control three or more permanents you don't own, draw three cards.

Cloudkin Seer

Flying
When Cloudkin Seer enters, draw a card.

Island

Air Elemental

Captivating Gyre

Return up to three target creatures to their owners' hands.

Winged Words

This spell costs {1} less to cast if you control a creature with flying.
Draw two cards.

Howling Golem

Whenever Howling Golem attacks or blocks, each player draws a card.

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.

Dungeon Geists

Flying
When Dungeon Geists enters, tap target creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control Dungeon Geists.

Dramatic Reversal

Untap all nonland permanents you control.

Sphinx of Enlightenment

Flying
When Sphinx of Enlightenment enters, target opponent draws a card and you draw three cards.

Decision Paralysis

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.

Cryptic Serpent

This spell costs {1} less to cast for each instant and sorcery card in your graveyard.

Rise from the Tides

Create a tapped 2/2 black Zombie creature token for each instant and sorcery card in your graveyard.

Salvager of Secrets

When Salvager of Secrets enters, return target instant or sorcery card from your graveyard to your hand.

Galestrike

Return target tapped creature to its owner's hand.
Draw a card.

Moat Piranhas

River's Rebuke

Return all nonland permanents target player controls to their owner's hand.

Aven Wind Mage

Flying
Whenever you cast an instant or sorcery spell, Aven Wind Mage gets +1/+1 until end of turn.

Engulf the Shore

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

Frost Lynx

When Frost Lynx enters, tap target creature an opponent controls. That creature doesn't untap during its controller's next untap step.

Claustrophobia

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