Myriad Landscape

This land enters tapped.
{T}: Add {C}.
{2}, {T}, Sacrifice this land: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

Lord of Atlantis

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

Tidebinder Mage

When this creature enters, tap target red or green creature an opponent controls. That creature doesn't untap during its controller's untap step for as long as you control this creature.

Spellskite

{U/P}: Change a target of target spell or ability to this creature. ({U/P} can be paid with either {U} or 2 life.)

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.

Prohibit

Kicker {2} (You may pay an additional {2} as you cast this spell.)
Counter target spell if its mana value is 2 or less. If this spell was kicked, counter that spell if its mana value is 4 or less instead.

True-Name Nemesis

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

Phantasmal Image

You may have this creature enter as a copy of any creature on the battlefield, except it's an Illusion in addition to its other types and it has "When this creature becomes the target of a spell or ability, sacrifice it."

Cursecatcher

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

Arcane Denial

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep.
You draw a card at the beginning of the next turn's upkeep.

Swan Song

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

Imprisoned in the Moon

Enchant creature, land, or planeswalker
Enchanted permanent is a colorless land with "{T}: Add {C}" and loses all other card types and abilities.

Mental Misstep

({U/P} can be paid with either {U} or 2 life.)
Counter target spell with mana value 1.

Island

Brainstorm

Draw three cards, then put two cards from your hand on top of your library in any order.

Merrow Reejerey

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

Vapor Snag

Return target creature to its owner's hand. Its controller loses 1 life.

Spreading Seas

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

Remand

Counter target spell. If that spell is countered this way, put it into its owner's hand instead of into that player's graveyard.
Draw a card.

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.)

Mana Leak

Counter target spell unless its controller pays {3}.

Turn Aside

Counter target spell that targets a permanent you control.

Homeward Path

{T}: Add {C}.
{T}: Each player gains control of all creatures they own.

Steel Sabotage

Choose one —
• Counter target artifact spell.
• Return target artifact to its owner's hand.

Merfolk Sovereign

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

Redirect

You may choose new targets for target spell.

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.

Ponder

Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.

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.

Pongify

Destroy target creature. It can't be regenerated. Its controller creates a 3/3 green Ape creature token.

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.

Silvergill Adept

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

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.

Rapid Hybridization

Destroy target creature. It can't be regenerated. That creature's controller creates a 3/3 green Frog Lizard creature token.

Mutavault

{T}: Add {C}.
{1}: This land becomes a 2/2 creature with all creature types until end of turn. It's still a land.

Negate

Seasinger

When you control no Islands, sacrifice this creature.
You may choose not to untap this creature during your untap step.
{T}: Gain control of target creature whose controller controls an Island for as long as you control this creature and this creature remains tapped.

Counterspell

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.

Maze of Ith

{T}: Untap target attacking creature. Prevent all combat damage that would be dealt to and dealt by that creature this turn.

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.)

Merrow Commerce

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

Annul

Counter target artifact or enchantment spell.

Hibernation

Return all green permanents to their owners' hands.

Kira, Great Glass-Spinner

Flying
Creatures you control have "Whenever this creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability."

Deprive

As an additional cost to cast this spell, return a land you control to its owner's hand.
Counter target spell.