Counterspell

Deeproot Wayfinder

Whenever Deeproot Wayfinder deals combat damage to a player or battle, surveil 1, then you may return a land card from your graveyard to the battlefield tapped. (To surveil 1, look at the top card of your library. You may put that card into your graveyard.)

Quest for Renewal

Whenever a creature you control becomes tapped, you may put a quest counter on Quest for Renewal.
As long as there are four or more quest counters on Quest for Renewal, untap all creatures you control during each other player's untap step.

Seedborn Muse

Untap all permanents you control during each other player's untap step.

Quandrix Campus

Quandrix Campus enters tapped.
{T}: Add {G} or {U}.
{4}, {T}: Scry 1.

Sol Ring

Deeproot Elite

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

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.

Merfolk Sovereign

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

Omniscience

You may cast spells from your hand without paying their mana costs.

Lumbering Falls

Lumbering Falls enters tapped.
{T}: Add {G} or {U}.
{2}{G}{U}: Lumbering Falls becomes a 3/3 green and blue Elemental creature with hexproof until end of turn. It's still a land.

Quicksilver Fountain

At the beginning of each player's upkeep, that player puts a flood counter on target non-Island land they control of their choice. That land is an Island for as long as it has a flood counter on it.
At the beginning of each end step, if all lands on the battlefield are Islands, remove all flood counters from them.

Island

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.)

Arcane Signet

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

Dramatic Reversal

Untap all nonland permanents you control.

Seafloor Oracle

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

Silvergill Adept

As an additional cost to cast this spell, reveal a Merfolk card from your hand or pay {3}.
When Silvergill Adept enters, draw a card.

Littjara Mirrorlake

Littjara Mirrorlake enters tapped.
{T}: Add {U}.
{2}{G}{G}{U}, {T}, Sacrifice Littjara Mirrorlake: Create a token that's a copy of target creature you control, except it enters with an additional +1/+1 counter on it. Activate only as a sorcery.

Harrow

As an additional cost to cast this spell, sacrifice a land.
Search your library for up to two basic land cards, put them onto the battlefield, then shuffle.

Llanowar Elves

Svyelun of Sea and Sky

Svyelun of Sea and Sky 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}.)

Kiora, Master of the Depths

+1: Untap up to one target creature and up to one target land.
−2: Reveal the top four cards of your library. You may put a creature card and/or a land card from among them into your hand. Put the rest into your graveyard.
−8: You get an emblem with "Whenever a creature you control enters, you may have it fight target creature." Then create three 8/8 blue Octopus creature tokens.

Merfolk Mistbinder

Vineglimmer Snarl

As Vineglimmer Snarl enters, you may reveal a Forest or Island card from your hand. If you don't, Vineglimmer Snarl enters tapped.
{T}: Add {G} or {U}.

Murkfiend Liege

Other green creatures you control get +1/+1.
Other blue creatures you control get +1/+1.
Untap all green and/or blue creatures you control during each other player's untap step.

Rhystic Study

Whenever an opponent casts a spell, you may draw a card unless that player pays {1}.

Merrow Reejerey

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

Wilderness Reclamation

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

Hinterland Harbor

Hinterland Harbor enters tapped unless you control a Forest or an Island.
{T}: Add {G} or {U}.

Rimewood Falls

({T}: Add {G} or {U}.)
Rimewood Falls enters tapped.

Cold-Eyed Selkie

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

Temple of Mystery

Temple of Mystery enters tapped.
When Temple of Mystery enters, scry 1.
{T}: Add {G} or {U}.

Tide Shaper

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

Hypergenesis

Suspend 3—{1}{G}{G}
Starting with you, each player may put an artifact, creature, enchantment, or land card from their hand onto the battlefield. Repeat this process until no one puts a card onto the battlefield.

Cryptolith Rite

Creatures you control have "{T}: Add one mana of any color."

Isochron Scepter

Imprint — When Isochron Scepter enters, you may exile an instant card with mana value 2 or less from your hand.
{2}, {T}: You may copy the exiled card. If you do, you may cast the copy without paying its mana cost.

Fleet Swallower

Whenever Fleet Swallower attacks, target player mills half their library, rounded up.

Cursecatcher

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

Coral Helm

{3}, Discard a card at random: Target creature gets +2/+2 until end of turn.

Forerunner of the Heralds

When Forerunner of the Heralds 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 Forerunner of the Heralds.

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.)

Command Tower

Thassa's Oracle

When Thassa's Oracle 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.)

Trinket Mage

When Trinket Mage enters, you may search your library for an artifact card with mana value 1 or less, reveal that card, put it into your hand, then shuffle.

Skyshroud Forest

Skyshroud Forest enters tapped.
{T}: Add {C}.
{T}: Add {G} or {U}. Skyshroud Forest deals 1 damage to you.

Simic Signet

Abundance

If you would draw a card, you may instead choose land or nonland and reveal cards from the top of your library until you reveal a card of the chosen kind. Put that card into your hand and put all other cards revealed this way 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}.

Kiora, the Crashing Wave

+1: Until your next turn, prevent all damage that would be dealt to and dealt by target permanent an opponent controls.
−1: Draw a card. You may play an additional land this turn.
−5: You get an emblem with "At the beginning of your end step, create a 9/9 blue Kraken creature token."

Merrow Commerce

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

Tidechannel Pathway

Barkchannel Pathway

Barkchannel Pathway // Tidechannel Pathway

Forest

Reliquary Tower

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

Exotic Orchard

{T}: Add one mana of any color that a land an opponent controls could produce.

Worldly Tutor

Search your library for a creature card, reveal it, then shuffle and put the card on top.

Managorger Hydra

Trample
Whenever a player casts a spell, put a +1/+1 counter on Managorger Hydra.

Tiller Engine

Whenever a land you control enters tapped, choose one —
• Untap that land.
• Tap target nonland permanent an opponent controls.

Mystical Tutor

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

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.

Beast Within

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

Spreading Seas

Enchant land
When Spreading Seas enters, draw a card.
Enchanted land is an Island.

Reflections of Littjara

As Reflections of Littjara 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.)

Kodama's Reach

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.

Simic Growth Chamber

Simic Growth Chamber enters tapped.
When Simic Growth Chamber enters, return a land you control to its owner's hand.
{T}: Add {G}{U}.

Leyline of Anticipation

If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield.
You may cast spells as though they had flash.

Time of Need

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

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.

Solemn Simulacrum

When Solemn Simulacrum enters, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
When Solemn Simulacrum dies, you may draw a card.

Evacuation

Return all creatures to their owners' hands.

Sakura-Tribe Elder

Sacrifice Sakura-Tribe Elder: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Enter the Infinite

Draw cards equal to the number of cards in your library, then put a card from your hand on top of your library. You have no maximum hand size until your next turn.

Herald of Secret Streams

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

Kumena, Tyrant of Orazca

Tap another untapped Merfolk you control: Kumena, Tyrant of Orazca 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.

True-Name Nemesis

As True-Name Nemesis enters, choose a player.
True-Name Nemesis has protection from the chosen player.

Rampant Growth

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

Flooded Grove

{T}: Add {C}.
{G/U}, {T}: Add {G}{G}, {G}{U}, or {U}{U}.

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.

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.

Herald's Horn

As Herald's Horn enters, choose a creature type.
Creature spells you cast of the chosen type cost {1} less to cast.
At the beginning of your upkeep, look at the top card of your library. If it's a creature card of the chosen type, you may reveal it and put it into your hand.