Don't Have

Wave of Reckoning

Each creature deals damage to itself equal to its power.

Have

Merrow Commerce

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

Umezawa's Jitte

Whenever equipped creature deals combat damage, put two charge counters on Umezawa's Jitte.
Remove a charge counter from Umezawa's Jitte: Choose one —
• Equipped creature gets +2/+2 until end of turn.
• Target creature gets -1/-1 until end of turn.
• You gain 2 life.
Equip {2}

Counterspell

Tidal Warrior

{T}: Target land becomes an Island until end of turn.

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}.)

Sol Ring

Getting

Lord of Atlantis

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

Fallowsage

Whenever this creature becomes tapped, you may draw a card.

Prismatic Vista

{T}, Pay 1 life, Sacrifice this land: Search your library for a basic land card, put it onto the battlefield, then shuffle.

Mist Dancer

Flying
Other Merfolk you control get +1/+0 and have flying.
Encore {5}{U}{U} ({5}{U}{U}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

Island

Wanderwine Hub

As this land enters, you may reveal a Merfolk card from your hand. If you don't, this land enters tapped.
{T}: Add {W} or {U}.

Pongify

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

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.

Ring of Thune

Equipped creature has vigilance. (Attacking doesn't cause it to tap.)
At the beginning of your upkeep, put a +1/+1 counter on equipped creature if it's white.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

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.

Hallowed Fountain

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

Patron Wizard

Tap an untapped Wizard you control: Counter target spell unless its controller pays {1}.

Seafloor Oracle

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

Adarkar Wastes

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

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Stonybrook Schoolmaster

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

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}.

Stoneforge Masterwork

Equipped creature gets +1/+1 for each other creature you control that shares a creature type with it.
Equip {2}

Explorer's Scope

Whenever equipped creature attacks, look at the top card of your library. If it's a land card, you may put it onto the battlefield tapped.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Blackblade Reforged

Equipped creature gets +1/+1 for each land you control.
Equip legendary creature {3}
Equip {7}

Streambed Aquitects

{T}: Target Merfolk creature gets +1/+1 and gains islandwalk until end of turn. (It can't be blocked as long as defending player controls an Island.)
{T}: Target land becomes an Island until end of turn.

Door of Destinies

As this artifact enters, choose a creature type.
Whenever you cast a spell of the chosen type, put a charge counter on this artifact.
Creatures you control of the chosen type get +1/+1 for each charge counter on this artifact.

Mindspring Merfolk

Exhaust — {X}{U}{U}, {T}: Draw X cards. Put a +1/+1 counter on each Merfolk creature you control. (Activate each exhaust ability only once.)

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.

Command Tower

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

Wayfarer's Bauble

{2}, {T}, Sacrifice this artifact: Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

Skullclamp

Equipped creature gets +1/-1.
Whenever equipped creature dies, draw two cards.
Equip {1}

Enclave Cryptologist

Level up {1}{U} ({1}{U}: Put a level counter on this. Level up only as a sorcery.)
LEVEL 1-2
0/1
{T}: Draw a card, then discard a card.
LEVEL 3+
0/1
{T}: Draw a card.

Seachrome Coast

This land enters tapped unless you control two or fewer other lands.
{T}: Add {W} or {U}.

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.

Bloodforged Battle-Axe

Equipped creature gets +2/+0.
Whenever equipped creature deals combat damage to a player, create a token that's a copy of this Equipment.
Equip {2}

Mirror Entity

Changeling (This card is every creature type.)
{X}: Until end of turn, creatures you control have base power and toughness X/X and gain all creature types.

Diviner's Wand

Equipped creature has "Whenever you draw a card, this creature gets +1/+1 and gains flying until end of turn" and "{4}: Draw a card."
Whenever a Wizard creature enters, you may attach this Equipment to it.
Equip {3}

Brainstorm

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

Glacial Fortress

This land enters tapped unless you control a Plains or an Island.
{T}: Add {W} or {U}.

Sword of the Animist

Equipped creature gets +1/+1.
Whenever equipped creature attacks, you may search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
Equip {2}

Plains

Wanderwine Prophets

Champion a Merfolk (When this enters, sacrifice it unless you exile another Merfolk you control. When this leaves the battlefield, that card returns to the battlefield.)
Whenever this creature deals combat damage to a player, you may sacrifice a Merfolk. If you do, take an extra turn after this one.

Sigil of Valor

Whenever equipped creature attacks alone, it gets +1/+1 until end of turn for each other creature you control.
Equip {1} ({1}: Attach to target creature you control. Equip only as a sorcery.)

Paradise Mantle

Equipped creature has "{T}: Add one mana of any color."
Equip {1}

Tideshaper Mystic

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

Seahunter

{3}, {T}: Search your library for a Merfolk permanent card, put it onto the battlefield, then shuffle.

Whirlpool Rider

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

Nimbus Maze

{T}: Add {C}.
{T}: Add {W}. Activate only if you control an Island.
{T}: Add {U}. Activate only if you control a Plains.

Swords to Plowshares

Exile target creature. Its controller gains life equal to its power.

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.

Tishana's Tidebinder

Flash
When this creature enters, counter up to one target activated or triggered ability. If an ability of an artifact, creature, or planeswalker is countered this way, that permanent loses all abilities for as long as this creature remains on the battlefield. (Mana abilities can't be targeted.)

Flare of Denial

You may sacrifice a nontoken blue creature rather than pay this spell's mana cost.
Counter target spell.

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.

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.

Merfolk Sovereign

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

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.

Path of Ancestry

This land enters tapped.
{T}: Add one mana of any color in your commander's color identity. When that mana is spent to cast a creature spell that shares a creature type with your commander, scry 1. (Look at the top card of your library. You may put that card on the bottom.)

Merrow Reejerey

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

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.

Evacuation

Return all creatures to their owners' hands.

Mystic Gate

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

Dovin's Veto

This spell can't be countered.
Counter target noncreature spell.

Surgespanner

Whenever this creature becomes tapped, you may pay {1}{U}. If you do, return target permanent to its owner's hand.

Sword of Feast and Famine

Equipped creature gets +2/+2 and has protection from black and from green.
Whenever equipped creature deals combat damage to a player, that player discards a card and you untap all lands you control.
Equip {2}

Merfolk Looter

Windfall

Each player discards their hand, then draws cards equal to the greatest number of cards a player discarded this way.

Swan Song

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

Flooded Strand

{T}, Pay 1 life, Sacrifice this land: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.

Vodalian Wave-Knight

Whenever you draw a card, put a +1/+1 counter on each other Merfolk and/or Knight you control.

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.)

Sage of Fables

Each other Wizard creature you control enters with an additional +1/+1 counter on it.
{2}, Remove a +1/+1 counter from a creature you control: Draw a card.

Fireshrieker

Equipped creature has double strike. (It deals both first-strike and regular combat damage.)
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

Inquisitor's Flail

If equipped creature would deal combat damage, it deals double that damage instead.
If another creature would deal combat damage to equipped creature, it deals double that damage to equipped creature instead.
Equip {2}

Skycloud Expanse

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.

Springleaf Drum

{T}, Tap an untapped creature you control: Add one mana of any color.

Vodalian Hexcatcher

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