Rootwater Thief

{U}: This creature gains flying until end of turn.
Whenever this creature deals combat damage to a player, you may pay {2}. If you do, search that player's library for a card and exile it, then the player shuffles.

Daze

You may return an Island you control to its owner's hand rather than pay this spell's mana cost.
Counter target spell unless its controller pays {1}.

Gush

You may return two Islands you control to their owner's hand rather than pay this spell's mana cost.
Draw two cards.

Annul

Counter target artifact or enchantment spell.

Reef Shaman

{T}: Target land becomes the basic land type of your choice until end of turn.

Waterfront Bouncer

{U}, {T}, Discard a card: Return target creature to its owner's hand.

Back to Basics

Nonbasic lands don't untap during their controllers' untap steps.

Chill

Counterspell

Foil

You may discard an Island card and another card rather than pay this spell's mana cost.
Counter target spell.

Winter Orb

As long as this artifact is untapped, players can't untap more than one land during their untap steps.

Misdirection

You may exile a blue card from your hand rather than pay this spell's mana cost.
Change the target of target spell with a single target.

Curiosity

Enchant creature
Whenever enchanted creature deals damage to an opponent, you may draw a card.

Tidal Warrior

{T}: Target land becomes an Island until end of turn.

Island

Lord of Atlantis

Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)

Opposition

Tap an untapped creature you control: Tap target artifact, creature, or land.

Boomerang

Return target permanent to its owner's hand.

Blue Elemental Blast

Choose one —
• Counter target red spell.
• Destroy target red permanent.

Tormod's Crypt

{T}, Sacrifice this artifact: Exile target player's graveyard.