Have

Rite of Replication

Kicker {5} (You may pay an additional {5} as you cast this spell.)
Create a token that's a copy of target creature. If this spell was kicked, create five of those tokens instead.

Harbinger of the Tides

You may cast this card as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.)
When this creature enters, you may return target tapped creature an opponent controls to its owner's hand.

Clear the Mind

Target player shuffles their graveyard into their library.
Draw a card.

Deepglow Skate

When this creature enters, double the number of each kind of counter on any number of target permanents.

Don't Have

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.

Moonring Island

({T}: Add {U}.)
This land enters tapped.
{U}, {T}: Look at the top card of target player's library. Activate only if you control two or more blue permanents.

Cosi's Trickster

Whenever an opponent shuffles their library, you may put a +1/+1 counter on this creature.

Ink Dissolver

Kinship — At the beginning of your upkeep, you may look at the top card of your library. If it shares a creature type with this creature, you may reveal it. If you do, each opponent mills three cards.

Sapphire Medallion

Blue spells you cast cost {1} less to cast.

Propaganda

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Inkfathom Divers

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
When this creature enters, look at the top four cards of your library, then put them back in any order.

Merrow Commerce

At the beginning of your end step, untap all Merfolk you control.

Drag Under

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

Merrow Harbinger

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
When this creature enters, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top.

Reflections of Littjara

As this enchantment enters, choose a creature type.
Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Stream of Thought

Target player mills four cards. You shuffle up to four cards from your graveyard into your library.
Replicate {2}{U}{U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)

Merfolk Trickster

Flash
When this creature enters, tap target creature an opponent controls. It loses all abilities until end of turn.

Dive Down

Target creature you control gets +0/+3 and gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Slinn Voda, the Rising Deep

Kicker {1}{U} (You may pay an additional {1}{U} as you cast this spell.)
When Slinn Voda enters, if it was kicked, return all creatures to their owners' hands except for Merfolk, Krakens, Leviathans, Octopuses, and Serpents.

Flow of Knowledge

Draw a card for each Island you control, then discard two cards.

Mirror Match

Cast this spell only during the declare blockers step.
For each creature attacking you or a planeswalker you control, create a token that's a copy of that creature and that's blocking that creature. Exile those tokens at end of combat.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Breakthrough

Draw four cards, then choose X cards in your hand and discard the rest.

Crashing Tide

This spell has flash as long as you control a Merfolk.
Return target creature to its owner's hand.
Draw a card.

Harbinger of the Seas

Merfolk Wayfinder

Flying
When this creature enters, reveal the top three cards of your library. Put all Island cards revealed this way into your hand and the rest on the bottom of your library in any order.

Merfolk Sovereign

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

Thassa's Rebuff

Counter target spell unless its controller pays {X}, where X is your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Lose Focus

Replicate {U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Counter target spell unless its controller pays {2}.

Admiral's Order

Raid — If you attacked this turn, you may pay {U} rather than pay this spell's mana cost.
Counter target spell.

Reliquary Tower

You have no maximum hand size.
{T}: Add {C}.

Deeptread Merrow

{U}: This creature gains islandwalk until end of turn. (It can't be blocked as long as defending player controls an Island.)

Island

Copy

(This token can be used to represent a token that's a copy of a permanent.)

Merfolk Assassin

{T}: Destroy target creature with islandwalk.

Serpent of the Endless Sea

Serpent of the Endless Sea's power and toughness are each equal to the number of Islands you control.
This creature can't attack unless defending player controls an Island.

Stormtide Leviathan

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.

Enclave Elite

Multikicker {1}{U} (You may pay an additional {1}{U} any number of times as you cast this spell.)
Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
This creature enters with a +1/+1 counter on it for each time it was kicked.

Preordain

Scry 2, then draw a card. (To 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.)

Benthic Explorers

{T}, Untap a tapped land an opponent controls: Add one mana of any type that land could produce.

Breaking Wave

You may cast this spell as though it had flash if you pay {2} more to cast it. (You may cast it any time you could cast an instant.)
Simultaneously untap all tapped creatures and tap all untapped creatures.

Midnight Clock

{T}: Add {U}.
{2}{U}: Put an hour counter on this artifact.
At the beginning of each upkeep, put an hour counter on this artifact.
When the twelfth hour counter is put on this artifact, shuffle your hand and graveyard into your library, then draw seven cards. Exile this artifact.

Halimar Depths

This land enters tapped.
When this land enters, look at the top three cards of your library, then put them back in any order.
{T}: Add {U}.

Filter Out

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

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.

Chart a Course

Draw two cards. Then discard a card unless you attacked this turn.

Merfolk Mesmerist

Drowner of Secrets

Tap an untapped Merfolk you control: Target player mills a card.

Deeproot Pilgrimage

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

Deeproot Waters

Whenever you cast a Merfolk spell, create a 1/1 blue Merfolk creature token with hexproof. (A creature with hexproof can't be the target of spells or abilities your opponents control.)

Calamitous Tide

Return up to two target creatures to their owners' hands. Draw two cards, then discard a card.

Svyelun of Sea and Sky

Svyelun has indestructible as long as you control at least two other Merfolk.
Whenever Svyelun attacks, draw a card.
Other Merfolk you control have ward {1}. (Whenever another Merfolk you control becomes the target of a spell or ability an opponent controls, counter it unless that player pays {1}.)

Aquatic Incursion

When this enchantment enters, create two 1/1 blue Merfolk creature tokens with hexproof. (They can't be the targets of spells or abilities your opponents control.)
{3}{U}: Target Merfolk can't be blocked this turn.

Drowner Initiate

Whenever a player casts a blue spell, you may pay {1}. If you do, target player mills two cards.

Cursecatcher

Sacrifice this creature: Counter target instant or sorcery spell unless its controller pays {1}.

Augur of Bolas

When this creature enters, look at the top three cards of your library. You may reveal an instant or sorcery card from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Vodalian Hexcatcher

Flash
Other Merfolk you control get +1/+1.
Sacrifice a Merfolk: Counter target noncreature spell unless its controller pays {1}.

Pull from the Deep

Return up to one target instant card and up to one target sorcery card from your graveyard to your hand. Exile Pull from the Deep.

Merfolk

Hexproof (This creature can't be the target of spells or abilities your opponents control.)

Lonely Sandbar

This land enters tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Gigadrowse

Replicate {U} (When you cast this spell, copy it for each time you paid its replicate cost. You may choose new targets for the copies.)
Tap target permanent.

Annul

Counter target artifact or enchantment spell.

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}.

Emperor Mihail II

You may look at the top card of your library any time.
You may cast Merfolk spells from the top of your library.
Whenever you cast a Merfolk spell, you may pay {1}. If you do, create a 1/1 blue Merfolk creature token.

Svyelunite Temple

This land enters tapped.
{T}: Add {U}.
{T}, Sacrifice this land: Add {U}{U}.

Tromokratis

Tromokratis has hexproof unless it's attacking or blocking.
Tromokratis can't be blocked unless all creatures defending player controls block it. (If any creature that player controls doesn't block this creature, it can't be blocked.)

Grappling Kraken

Landfall — Whenever a land you control enters, tap target creature an opponent controls and put a stun counter on it. (If a permanent with a stun counter would become untapped, remove one from it instead.)

Mystic Sanctuary

({T}: Add {U}.)
This land enters tapped unless you control three or more other Islands.
When this land enters untapped, you may put target instant or sorcery card from your graveyard on top of your library.

Kopala, Warden of Waves

Spells your opponents cast that target a Merfolk you control cost {2} more to cast.
Abilities your opponents activate that target a Merfolk you control cost {2} more to activate.

Merrow Levitator

{T}: Target creature gains flying until end of turn.
Whenever you cast a blue spell, you may untap this creature.

Dakra Mystic

{U}, {T}: Each player reveals the top card of their library. You may put the revealed cards into their owners' graveyards. If you don't, each player draws a card.

High Tide

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

Spreading Seas

Enchant land
When this Aura enters, draw a card.
Enchanted land is an Island.

Convincing Mirage

Enchant land
As this Aura enters, choose a basic land type.
Enchanted land is the chosen type.

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.

Deepchannel Mentor

Blue creatures you control can't be blocked.

Bident of Thassa

Whenever a creature you control deals combat damage to a player, you may draw a card.
{1}{U}, {T}: Creatures your opponents control attack this turn if able.

Merrow Reejerey

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

Master of the Pearl Trident

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