Merseine

Enchant creature
Merseine enters the battlefield with three net counters on it.
Enchanted creature doesn't untap during its controller's untap step if Merseine has a net counter on it.
Pay enchanted creature's mana cost: Remove a net counter from Merseine. Only the controller of the enchanted creature may activate this ability.

Rootwater Diver

{T}, Sacrifice Rootwater Diver: Return target artifact card from your graveyard to your hand.

Arch of Orazca

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
{T}: Add {C}.
{5}, {T}: Draw a card. Activate only if you have the city's blessing.

Vodalian War Machine

Defender (This creature can't attack.)
Tap an untapped Merfolk you control: Vodalian War Machine can attack this turn as though it didn't have defender.
Tap an untapped Merfolk you control: Vodalian War Machine gets +2/+1 until end of turn.
When Vodalian War Machine dies, destroy all Merfolk tapped this turn to pay for its abilities.

Crown of Ascension

Enchant creature
Enchanted creature has flying.
Sacrifice Crown of Ascension: Enchanted creature and other creatures that share a creature type with it gain flying until end of turn.

Sol Ring

Rishadan Dockhand

Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
{1}, {T}: Tap target land.

Ponder

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

Sky Diamond

Sky Diamond enters the battlefield tapped.
{T}: Add {U}.

Lingering Mirage

Enchant land
Enchanted land is an Island.
Cycling {2} ({2}, Discard this card: Draw a card.)

Peer Pressure

Choose a creature type. If you control more creatures of that type than each other player, you gain control of all creatures of that type. (This effect lasts indefinitely.)

Saprazzan Cove

Saprazzan Cove enters the battlefield tapped.
{T}: Put a storage counter on Saprazzan Cove.
{T}, Remove any number of storage counters from Saprazzan Cove: Add {U} for each storage counter removed this way.

Sand Silos

Sand Silos enters the battlefield tapped.
You may choose not to untap Sand Silos during your untap step.
At the beginning of your upkeep, if Sand Silos is tapped, put a storage counter on it.
{T}, Remove any number of storage counters from Sand Silos: Add {U} for each storage counter removed this way.

Svyelunite Temple

Svyelunite Temple enters the battlefield tapped.
{T}: Add {U}.
{T}, Sacrifice Svyelunite Temple: Add {U}{U}.

Faces of the Past

Whenever a creature dies, tap all untapped creatures that share a creature type with it or untap all tapped creatures that share a creature type with it.

Saprazzan Legate

If an opponent controls a Mountain and you control an Island, you may cast this spell without paying its mana cost.
Flying

Disdainful Stroke

Counter target spell with mana value 4 or greater.

Tangle Kelp

Enchant creature
When Tangle Kelp enters the battlefield, tap enchanted creature.
Enchanted creature doesn't untap during its controller's untap step if it attacked during its controller's last turn.

Vodalian Illusionist

{U}{U}, {T}: Target creature phases out. (While it's phased out, it's treated as though it doesn't exist. It phases in before its controller untaps during their next untap step.)

Remote Isle

Remote Isle enters the battlefield tapped.
{T}: Add {U}.
Cycling {2} ({2}, Discard this card: Draw a card.)

War Barge

{3}: Target creature gains islandwalk until end of turn. When War Barge leaves the battlefield this turn, destroy that creature. A creature destroyed this way can't be regenerated. (A creature with islandwalk can't be blocked as long as defending player controls an Island.)

Mystic Confluence

Choose three. You may choose the same mode more than once.
• Counter target spell unless its controller pays {3}.
• Return target creature to its owner's hand.
• Draw a card.

Magical Hack

Change the text of target spell or permanent by replacing all instances of one basic land type with another. (For example, you may change "swampwalk" to "plainswalk." This effect lasts indefinitely.)

Rootwater Matriarch

{T}: Gain control of target creature for as long as that creature is enchanted.

Sunken City

At the beginning of your upkeep, sacrifice Sunken City unless you pay {U}{U}.
Blue creatures get +1/+1.

Saprazzan Heir

Whenever Saprazzan Heir becomes blocked, you may draw three cards.

Mystic Sanctuary

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

Counterspell

Coral Atoll

Coral Atoll enters the battlefield tapped.
When Coral Atoll enters the battlefield, sacrifice it unless you return an untapped Island you control to its owner's hand.
{T}: Add {C}{U}.

Talrand, Sky Summoner

Whenever you cast an instant or sorcery spell, create a 2/2 blue Drake creature token with flying.

Benthic Explorers

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

Vodalian Knights

First strike
Vodalian Knights can't attack unless defending player controls an Island.
When you control no Islands, sacrifice Vodalian Knights.
{U}: Vodalian Knights gains flying until end of turn.

Merfolk Assassin

{T}: Destroy target creature with islandwalk.

Seasinger

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

True-Name Nemesis

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

Arcane Signet

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

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.)

Saprazzan Skerry

Saprazzan Skerry enters the battlefield tapped with two depletion counters on it.
{T}, Remove a depletion counter from Saprazzan Skerry: Add {U}{U}. If there are no depletion counters on Saprazzan Skerry, sacrifice it.

Merfolk Looter

Rootwater Thief

{U}: Rootwater Thief gains flying until end of turn.
Whenever Rootwater Thief deals combat damage to a player, you may pay {2}. If you do, search that player's library for a card and exile it, then the player shuffles.

Brainstorm

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

Lat-Nam's Legacy

Shuffle a card from your hand into your library. If you do, draw two cards at the beginning of the next turn's upkeep.

River Merfolk

{U}: River Merfolk gains mountainwalk until end of turn. (It can't be blocked as long as defending player controls a Mountain.)

Rootwater Shaman

You may cast Aura spells with enchant creature as though they had flash.

Denizen of the Deep

When Denizen of the Deep enters the battlefield, return each other creature you control to its owner's hand.

Tidal Warrior

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

Vodalian Mage

{U}, {T}: Counter target spell unless its controller pays {1}.

Tidal Visionary

{T}: Target creature becomes the color of your choice until end of turn.

Marjhan

Marjhan doesn't untap during your untap step.
{U}{U}, Sacrifice a creature: Untap Marjhan. Activate only during your upkeep.
Marjhan can't attack unless defending player controls an Island.
{U}{U}: Marjhan gets -1/-0 until end of turn and deals 1 damage to target attacking creature without flying.
When you control no Islands, sacrifice Marjhan.

Island

Reef Shaman

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

Svyelunite Priest

{U}{U}, {T}: Target creature gains shroud until end of turn. Activate only during your upkeep. (It can't be the target of spells or abilities.)

Rootwater Mystic

{1}{U}: Look at the top card of target player's library.

Mana Short

Tap all lands target player controls and that player loses all unspent mana.

Lotus Bloom

Suspend 3—{0} (Rather than cast this card from your hand, pay {0} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
{T}, Sacrifice Lotus Bloom: Add three mana of any one color.

Overtaker

{3}{U}, {T}, Discard a card: Untap target creature and gain control of it until end of turn. That creature gains haste until end of turn.

Coral Fighters

Whenever Coral Fighters attacks and isn't blocked, look at the top card of defending player's library. You may put that card on the bottom of that player's library.

Lord of Atlantis

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

Merfolk of the Pearl Trident

Mana Vapors

Lands target player controls don't untap during their next untap step.

Erosion

Enchant land
At the beginning of the upkeep of enchanted land's controller, destroy that land unless that player pays {1} or 1 life.

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}.)

Phantasmal Terrain

Enchant land
As Phantasmal Terrain enters the battlefield, choose a basic land type.
Enchanted land is the chosen type.

Thing from the Deep

Whenever Thing from the Deep attacks, sacrifice it unless you sacrifice an Island.

Treasure Cruise

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.)
Draw three cards.

Inevitable Betrayal

Suspend 3—{1}{U}{U} (Rather than cast this card from your hand, pay {1}{U}{U} and exile it with three time counters on it. At the beginning of your upkeep, remove a time counter. When the last is removed, you may cast it without paying its mana cost.)
Search target opponent's library for a creature card and put that card onto the battlefield under your control. Then that player shuffles.

Tide Shaper

Kicker {1} (You may pay an additional {1} as you cast this spell.)
When Tide Shaper enters the battlefield, 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.

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.

Saprazzan Bailiff

When Saprazzan Bailiff enters the battlefield, exile all artifact and enchantment cards from all graveyards.
When Saprazzan Bailiff leaves the battlefield, return all artifact and enchantment cards from all graveyards to their owners' hands.

High Tide

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

Temple of the False God

{T}: Add {C}{C}. Activate only if you control five or more lands.

Seafloor Debris

Seafloor Debris enters the battlefield tapped.
{T}: Add {U}.
{T}, Sacrifice Seafloor Debris: Add one mana of any color.

Lonely Sandbar

Lonely Sandbar enters the battlefield tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)

Sea Scryer

Telepathy

Your opponents play with their hands revealed.

Volcanic Eruption

Destroy X target Mountains. Volcanic Eruption deals damage to each creature and each player equal to the number of Mountains put into a graveyard this way.