Into the Roil

Kicker {1}{U} (You may pay an additional {1}{U} as you cast this spell.)
Return target nonland permanent to its owner's hand. If this spell was kicked, draw a card.

Whirlpool Rider

When Whirlpool Rider enters, shuffle the cards from your hand into your library, then draw that many cards.

Flow of Ideas

Hammerhead Shark

Hammerhead Shark can't attack unless defending player controls an Island.

Retreat to Coralhelm

Landfall — Whenever a land you control enters, choose one —
• You may tap or untap target creature.
• Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Merfolk Sovereign

Other Merfolk creatures you control get +1/+1.
{T}: Target Merfolk creature can't be blocked this turn.

Coastal Breach

Undaunted (This spell costs {1} less to cast for each opponent.)
Return all nonland permanents to their owners' hands.

Tolarian Winds

Discard all the cards in your hand, then draw that many cards.

Water Elemental

Thassa's Intervention

Choose one —
• Look at the top X cards of your library. Put up to two of them into your hand and the rest on the bottom of your library in a random order.
• Counter target spell unless its controller pays twice {X}.

Noyan Dar, Roil Shaper

Whenever you cast an instant or sorcery spell, you may put three +1/+1 counters on target land you control. If you do, that land becomes a 0/0 Elemental creature with haste that's still a land.

Blustersquall

Tap target creature you don't control.
Overload {3}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

Fishliver Oil

Enchant creature (Target a creature as you cast this. This card enters attached to that creature.)
Enchanted creature has islandwalk. (It can't be blocked as long as defending player controls an Island.)

Kraken of the Straits

Creatures with power less than the number of Islands you control can't block Kraken of the Straits.

Displacement Wave

Return all nonland permanents with mana value X or less to their owners' hands.

Sea God's Revenge

Return up to three target creatures your opponents control to their owners' hands. Scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Force Away

Return target creature to its owner's hand.
Ferocious — If you control a creature with power 4 or greater, you may draw a card. If you do, discard a card.

Scattering Stroke

Counter target spell. Clash with an opponent. If you win, at the beginning of your next main phase, you may add an amount of {C} equal to that spell's mana value. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Mirror Image

You may have Mirror Image enter as a copy of a creature you control.

Gush

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

Colossal Whale

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Colossal Whale attacks, you may exile target creature defending player controls until Colossal Whale leaves the battlefield. (That creature returns under its owner's control.)

Tideshaper Mystic

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

Set Adrift

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Put target nonland permanent on top of its owner's library.

Captivating Gyre

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

Tidespout Tyrant

Flying
Whenever you cast a spell, return target permanent to its owner's hand.

Whirlpool Drake

Flying
When Whirlpool Drake enters, shuffle the cards from your hand into your library, then draw that many cards.
When Whirlpool Drake dies, shuffle the cards from your hand into your library, then draw that many cards.

Sunken City

At the beginning of your upkeep, sacrifice Sunken City unless you pay {U}{U}.
Blue creatures get +1/+1.

Waterwhirl

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

Mistform Wakecaster

Flying
{1}: Mistform Wakecaster becomes the creature type of your choice until end of turn.
{2}{U}{U}, {T}: Choose a creature type. Each creature you control becomes that type until end of turn.

Ominous Seas

Whenever you draw a card, put a foreshadow counter on Ominous Seas.
Remove eight foreshadow counters from Ominous Seas: Create an 8/8 blue Kraken creature token.
Cycling {2} ({2}, Discard this card: Draw a card.)

Sea Gate, Reborn

As Sea Gate, Reborn enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {U}.

Sea Gate Restoration

Draw cards equal to the number of cards in your hand plus one. You have no maximum hand size for the rest of the game.

Sea Gate Restoration // Sea Gate, Reborn

Clutch of Currents

Return target creature to its owner's hand.
Awaken 3—{4}{U} (If you cast this spell for {4}{U}, also put three +1/+1 counters on target land you control and it becomes a 0/0 Elemental creature with haste. It's still a land.)

Genju of the Falls

Enchant Island
{2}: Enchanted Island becomes a 3/2 blue Spirit creature with flying until end of turn. It's still a land.
When enchanted Island is put into a graveyard, you may return Genju of the Falls from your graveyard to your hand.

Tideforce Elemental

{U}, {T}: You may tap or untap another target creature.
Landfall — Whenever a land you control enters, you may untap Tideforce Elemental.

Whirlpool Whelm

Clash with an opponent, then return target creature to its owner's hand. If you win, you may put that creature on top of its owner's library instead. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

Depths of Desire

Return target creature to its owner's hand. Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Tide Drifter

Devoid (This card has no color.)
Other colorless creatures you control get +0/+1.

High Tide

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Sigiled Starfish

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

Waterspout Djinn

Flying
At the beginning of your upkeep, sacrifice Waterspout Djinn unless you return an untapped Island you control to its owner's hand.

Griptide

Put target creature on top of its owner's library.

Pirate's Prize

Draw two cards. Create a Treasure token. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")

Part the Waterveil

Take an extra turn after this one. Exile Part the Waterveil.
Awaken 6—{6}{U}{U}{U} (If you cast this spell for {6}{U}{U}{U}, also put six +1/+1 counters on target land you control and it becomes a 0/0 Elemental creature with haste. It's still a land.)

Tide Skimmer

Flying
Whenever you attack with two or more creatures with flying, draw a card.

Merfolk Assassin

{T}: Destroy target creature with islandwalk.

Water Servant

{U}: Water Servant gets +1/-1 until end of turn.
{U}: Water Servant gets -1/+1 until end of turn.

Nadir Kraken

Whenever you draw a card, you may pay {1}. If you do, put a +1/+1 counter on Nadir Kraken and create a 1/1 blue Tentacle creature token.

Canal Courier

When Canal Courier enters, you become the monarch.
Whenever Canal Courier and another creature attack different players, Canal Courier can't be blocked this combat.

Thirst for Meaning

Draw three cards. Then discard two cards unless you discard an enchantment card.

Dandân

Dandân can't attack unless defending player controls an Island.
When you control no Islands, sacrifice Dandân.

Riptide

Water Wurm

Water Wurm gets +0/+1 as long as an opponent controls an Island.

Tidewalker

Tidewalker enters with a time counter on it for each Island you control.
Vanishing (At the beginning of your upkeep, remove a time counter from this creature. When the last is removed, sacrifice it.)
Tidewalker's power and toughness are each equal to the number of time counters on it.

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.

Devastation Tide

Return all nonland permanents to their owners' hands.
Miracle {1}{U} (You may cast this card for its miracle cost when you draw it if it's the first card you drew this turn.)

Scourge of Fleets

When Scourge of Fleets 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.

Kindred Discovery

As Kindred Discovery enters, choose a creature type.
Whenever a creature you control of the chosen type enters or attacks, draw a card.

Engulf the Shore

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

Merrow Reejerey

Other Merfolk creatures you control get +1/+1.
Whenever you cast a Merfolk spell, you may tap or untap target permanent.

Erosion

Enchant land
At the beginning of the upkeep of enchanted land's controller, destroy that land unless that player pays {1} or 1 life.

Shark Typhoon

Whenever you cast a noncreature spell, create an X/X blue Shark creature token with flying, where X is that spell's mana value.
Cycling {X}{1}{U} ({X}{1}{U}, Discard this card: Draw a card.)
When you cycle Shark Typhoon, create an X/X blue Shark creature token with flying.

Part Water

X target creatures gain islandwalk until end of turn. (They can't be blocked as long as defending player controls an Island.)

Man-o'-War

When Man-o'-War enters, return target creature to its owner's hand.

Deep Water

{U}: Until end of turn, if you tap a land you control for mana, it produces {U} instead of any other type.

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.