Anticognition

Counter target creature or planeswalker spell unless its controller pays {2}. If an opponent has eight or more cards in their graveyard, instead counter that spell, then scry 2.

Tide Shaper

Kicker {1} (You may pay an additional {1} as you cast this spell.)
When this creature enters, if it was kicked, target land becomes an Island for as long as this creature remains on the battlefield.
This creature gets +1/+1 as long as an opponent controls an Island.

Moat Piranhas

Merfolk Looter

Bubble Up

Put target instant or sorcery card from your graveyard on top of your library. (Then exile this card. You may cast the creature later from exile.)

Aquatic Alchemist

Whenever you cast your first instant or sorcery spell each turn, this creature gets +2/+0 until end of turn.

Aquatic Alchemist // Bubble Up

Shipwreck Dowser

Prowess (Whenever you cast a noncreature spell, this creature gets +1/+1 until end of turn.)
When this creature enters, return target instant or sorcery card from your graveyard to your hand.

Merfolk Falconer

Flying
Whenever you cast a kicked spell, scry 2.

Skyswimmer Koi

Flying
Whenever an artifact you control enters, you may draw a card. If you do, discard a card.

Filter Out

Return all noncreature, nonland permanents to their owners' hands.

Merfolk Windrobber

Flying
Whenever this creature deals combat damage to a player, that player mills a card. (They put the top card of their library into their graveyard.)
Sacrifice this creature: Draw a card. Activate only if an opponent has eight or more cards in their graveyard.

Scuttletide

{1}, Discard a card: Create a 0/3 blue Crab creature token.
Delirium — Crabs you control get +1/+1 as long as there are four or more card types among cards in your graveyard.

Spined Megalodon

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
Whenever this creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Step Through

Return two target creatures to their owners' hands.
Wizardcycling {2} ({2}, Discard this card: Search your library for a Wizard card, reveal it, put it into your hand, then shuffle.)

Lagoon Breach

The owner of target attacking creature you don't control puts it on their choice of the top or bottom of their library.

Horned Loch-Whale

Flash
Ward {2}
This creature enters tapped unless it's your turn.

Horned Loch-Whale // Lagoon Breach

Island

Omen of the Sea

Flash (You may cast this spell any time you could cast an instant.)
When this enchantment enters, scry 2, then draw a card.
{2}{U}, Sacrifice this enchantment: 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.)

Coralhelm Chronicler

Whenever you cast a kicked spell, draw a card, then discard a card.
When this creature enters, look at the top five cards of your library. You may reveal a card with a kicker ability from among them and put it into your hand. Put the rest on the bottom of your library in a random order.

Cloud Manta

Merfolk Coralsmith

{1}: This creature gets +1/-1 until end of turn.
When this creature dies, scry 2.

Volshe Tideturner

{T}: Add {U}. Spend this mana only to cast an instant or sorcery spell or a kicked spell.

Tidepool Turtle

{2}{U}: Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

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.)

Steelfin Whale

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
Whenever an artifact you control enters, untap this creature.

Coral Merfolk

Hard Evidence

Create a 0/3 blue Crab creature token.
Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this token: Draw a card.")

Splashy Spellcaster

Whenever you cast an instant or sorcery spell, create a Sorcerer Role token attached to up to one other target creature you control. (If you control another Role on it, put that one into the graveyard. Enchanted creature gets +1/+1 and has "Whenever this creature attacks, scry 1.")

Riptide Turtle

Bubble Snare

Kicker {2}{U} (You may pay an additional {2}{U} as you cast this spell.)
Enchant creature
When this Aura enters, if it was kicked, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step.

Behold the Multiverse

Scry 2, then draw two cards.
Foretell {1}{U} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Cleric of Chill Depths

Whenever this creature blocks a creature, that creature doesn't untap during its controller's next untap step.

Freeze in Place

Tap target creature an opponent controls and put three stun counters on it. Scry 2. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Library Larcenist

Whenever this creature attacks, draw a card.

Octoprophet

When this creature enters, 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.)

Tidal Terror

Whenever this creature attacks, you may tap two other untapped creatures you control. If you do, this creature can't be blocked this turn.
Islandcycling {2} ({2}, Discard this card: Search your library for an Island card, reveal it, put it into your hand, then shuffle.)

Sure-Footed Infiltrator

Tap another untapped Rogue you control: This creature can't be blocked this turn.
Whenever this creature deals combat damage to a player, draw a card.

Skyclave Squid

Defender
Landfall — Whenever a land you control enters, this creature can attack this turn as though it didn't have defender.

Tazeem Roilmage

Kicker {4} (You may pay an additional {4} as you cast this spell.)
When this creature enters, if it was kicked, return target instant or sorcery card from your graveyard to your hand.

Mulldrifter

Flying
When this creature enters, draw two cards.
Evoke {2}{U} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Seafloor Stalker

{4}{U}: This creature gets +1/+0 until end of turn and can't be blocked this turn. This ability costs {1} less to activate for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Neutralize

Counter target spell.
Cycling {2} ({2}, Discard this card: Draw a card.)

Triton Shorethief

Deliberate

Expedition Diviner

Flying
As long as you control another Wizard, this creature has "When this creature dies, draw a card."

Scourge of Fleets

When this creature enters, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

The Reality Chip

You may look at the top card of your library any time.
As long as The Reality Chip is attached to a creature, you may play lands and cast spells from the top of your library.
Reconfigure {2}{U} ({2}{U}: Attach to target creature you control; or unattach from a creature. Reconfigure only as a sorcery. While attached, this isn't a creature.)

Ruin Crab

Landfall — Whenever a land you control enters, each opponent mills three cards. (To mill a card, a player puts the top card of their library into their graveyard.)

Cascade Seer

When this creature enters, scry X, where X is the number of creatures in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Deeproot Pilgrimage

Whenever one or more nontoken Merfolk you control become tapped, create a 1/1 blue Merfolk creature token with hexproof.

Expedition Lookout

Defender
As long as an opponent has eight or more cards in their graveyard, this creature can attack as though it didn't have defender and it can't be blocked.