Squid

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)

Stonybrook Banneret

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Merfolk spells and Wizard spells you cast cost {1} less to cast.

Aquitect's Will

Put a flood counter on target land. That land is an Island in addition to its other types for as long as it has a flood counter on it. If you control a Merfolk, draw a card.

Weather the Storm

You gain 3 life.
Storm (When you cast this spell, copy it for each spell cast before it this turn.)

Thornwood Falls

This land enters tapped.
When this land enters, you gain 1 life.
{T}: Add {G} or {U}.

Merfolk Spy

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever this creature deals combat damage to a player, that player reveals a card at random from their hand.

Prevent all combat damage that would be dealt this turn.

Forest

Return to Nature

Choose one —
• Destroy target artifact.
• Destroy target enchantment.
• Exile target card from a graveyard.

Frantic Inventory

Draw a card, then draw cards equal to the number of cards named Frantic Inventory in your graveyard.

Tormod's Crypt

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

Blue Elemental Blast

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

Snap

Return target creature to its owner's hand. Untap up to two lands.

Island

River Boa

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
{G}: Regenerate this creature.

Magnify

All creatures get +1/+1 until end of turn.

Coral Barrier

Defender (This creature can't attack.)
When this creature enters, create a 1/1 blue Squid creature token with islandwalk. (It can't be blocked as long as defending player controls an Island.)

Echoing Truth

Return target nonland permanent and all other permanents with the same name as that permanent to their owners' hands.