Eladamri's Call

Search your library for a creature card, reveal that card, put it into your hand, then shuffle.

Tropical Island

Sygg, River Guide

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
{1}{W}: Target Merfolk you control gains protection from the color of your choice until end of turn.

Azorius Signet

Adarkar Wastes

{T}: Add {C}.
{T}: Add {W} or {U}. This land deals 1 damage to you.

Sol Ring

Herald of Secret Streams

Creatures you control with +1/+1 counters on them can't be blocked.

Spreading Seas

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

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.

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.

Merfolk Branchwalker

When this creature enters, it explores. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard.)

Kiora's Follower

Lord of Atlantis

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

Hallowed Fountain

({T}: Add {W} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

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.

Thada Adel, Acquisitor

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever Thada Adel deals combat damage to a player, search that player's library for an artifact card and exile it. Then that player shuffles. Until end of turn, you may play that card.

Austere Command

Choose two —
• Destroy all artifacts.
• Destroy all enchantments.
• Destroy all creatures with mana value 3 or less.
• Destroy all creatures with mana value 4 or greater.

Beast Within

Destroy target permanent. Its controller creates a 3/3 green Beast creature token.

Fact or Fiction

Reveal the top five cards of your library. An opponent separates those cards into two piles. Put one pile into your hand and the other into your graveyard.

Counterspell

Tundra

Kumena, Tyrant of Orazca

Tap another untapped Merfolk you control: Kumena can't be blocked this turn.
Tap three untapped Merfolk you control: Draw a card.
Tap five untapped Merfolk you control: Put a +1/+1 counter on each Merfolk you control.

Shapers of Nature

{3}{G}: Put a +1/+1 counter on target creature.
{2}{U}, Remove a +1/+1 counter from a creature you control: Draw a card.

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.

Plains

Emry, Lurker of the Loch

Affinity for artifacts (This spell costs {1} less to cast for each artifact you control.)
When Emry enters, mill four cards.
{T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Thieving Skydiver

Kicker {X}. X can't be 0. (You may pay an additional {X} as you cast this spell.)
Flying
When this creature enters, if it was kicked, gain control of target artifact with mana value X or less. If that artifact is an Equipment, attach it to this creature.

Intruder Alarm

Creatures don't untap during their controllers' untap steps.
Whenever a creature enters, untap all creatures.

Simic Signet

Coralhelm Commander

Level up {1} ({1}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 2-3
3/3
Flying
LEVEL 4+
4/4
Flying
Other Merfolk creatures you control get +1/+1.

Library Larcenist

Whenever this creature attacks, draw a card.

Arcane Signet

{T}: Add one mana of any color in your commander's color identity.

Cultivate

Search your library for up to two basic land cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, then shuffle.

Cursecatcher

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

Temple Garden

({T}: Add {G} or {W}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

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.)

Return to Nature

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

Savannah

Merfolk Mistbinder

Generous Gift

Destroy target permanent. Its controller creates a 3/3 green Elephant creature token.

Command Tower

Return of the Wildspeaker

Choose one —
• Draw cards equal to the greatest power among non-Human creatures you control.
• Non-Human creatures you control get +3/+3 until end of turn.

Rampant Growth

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Chulane, Teller of Tales

Vigilance
Whenever you cast a creature spell, draw a card, then you may put a land card from your hand onto the battlefield.
{3}, {T}: Return target creature you control to its owner's hand.

Jade Bearer

When this creature enters, put a +1/+1 counter on another target Merfolk you control.

Unsettled Mariner

Changeling (This card is every creature type.)
Whenever you or a permanent you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {1}.

Drowner of Secrets

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

True-Name Nemesis

As this creature enters, choose a player.
This creature has protection from the chosen player.

Ambassador Laquatus

Judge of Currents

Whenever a Merfolk you control becomes tapped, you may gain 1 life.

Summon the School

Create two 1/1 blue Merfolk Wizard creature tokens.
Tap four untapped Merfolk you control: Return this card from your graveyard to your hand.

Kodama's Reach

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.

Teferi's Protection

Until your next turn, your life total can't change and you gain protection from everything. All permanents you control phase out. (While they're phased out, they're treated as though they don't exist. They phase in before you untap during your untap step.)
Exile Teferi's Protection.

Swan Song

Counter target enchantment, instant, or sorcery spell. Its controller creates a 2/2 blue Bird creature token with flying.

Path to Exile

Exile target creature. Its controller may search their library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Selesnya Signet

Stonybrook Schoolmaster

Whenever this creature becomes tapped, you may create a 1/1 blue Merfolk Wizard creature token.

Reality Shift

Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)

Forest

Combine Guildmage

{1}{G}, {T}: This turn, each creature you control enters with an additional +1/+1 counter on it.
{1}{U}, {T}: Move a +1/+1 counter from target creature you control onto another target creature you control.

Lullmage Mentor

Whenever a spell or ability you control counters a spell, you may create a 1/1 blue Merfolk creature token.
Tap seven untapped Merfolk you control: Counter target spell.

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.)

Jadelight Ranger

When this creature enters, it explores, then it explores again. (Reveal the top card of your library. Put that card into your hand if it's a land. Otherwise, put a +1/+1 counter on this creature, then put the card back or put it into your graveyard. Then repeat this process.)

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. This land deals 1 damage to you.

Mothdust Changeling

Changeling (This card is every creature type.)
Tap an untapped creature you control: This creature gains flying until end of turn.

Merrow Commerce

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

Vineshaper Mystic

When this creature enters, put a +1/+1 counter on each of up to two target Merfolk you control.

Benthic Biomancer

{1}{U}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.)
Whenever one or more +1/+1 counters are put on this creature, draw a card, then discard a card.

Thrasios, Triton Hero

{4}: Scry 1, then reveal the top card of your library. If it's a land card, put it onto the battlefield tapped. Otherwise, draw a card.
Partner (You can have two commanders if both have partner.)

Tatyova, Benthic Druid

Landfall — Whenever a land you control enters, you gain 1 life and draw a card.

Time Wipe

Return a creature you control to its owner's hand, then destroy all creatures.

Vorel of the Hull Clade

{G}{U}, {T}: Double the number of each kind of counter on target artifact, creature, or land.

Island

Castle Vantress

This land enters tapped unless you control an Island.
{T}: Add {U}.
{2}{U}{U}, {T}: Scry 2.

Wrath of God

Destroy all creatures. They can't be regenerated.

Coral Trickster

Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)
When this creature is turned face up, you may tap or untap target permanent.

Farseek

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Jade Guardian

Hexproof (This creature can't be the target of spells or abilities your opponents control.)
When this creature enters, put a +1/+1 counter on target Merfolk you control.

Mana Confluence

{T}, Pay 1 life: Add one mana of any color.

Seafloor Oracle

Whenever a Merfolk you control deals combat damage to a player, draw a card.

Growth Spiral

Draw a card. You may put a land card from your hand onto the battlefield.

Disallow

Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)

Cold-Eyed Selkie

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
Whenever this creature deals combat damage to a player, you may draw that many cards.

Breeding Pool

({T}: Add {G} or {U}.)
As this land enters, you may pay 2 life. If you don't, it enters tapped.

Forerunner of the Heralds

When this creature enters, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top.
Whenever another Merfolk you control enters, put a +1/+1 counter on this creature.

Deeproot Elite

Whenever another Merfolk you control enters, put a +1/+1 counter on target Merfolk you control.

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.

Krosan Grip

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.)
Destroy target artifact or enchantment.

Merfolk Trickster

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

Swift Warden

Flash
When this creature enters, target Merfolk you control gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Thassa's Oracle

When this creature enters, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)