Merfolk Sovereign

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

Pheres-Band Warchief

Vigilance, trample
Other Centaur creatures you control get +1/+1 and have vigilance and trample.

Lord of Atlantis

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

Diffusion Sliver

Whenever a Sliver creature you control becomes the target of a spell or ability an opponent controls, counter that spell or ability unless its controller pays {2}.

Growth Spiral

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

Descendants' Path

At the beginning of your upkeep, reveal the top card of your library. If it's a creature card that shares a creature type with a creature you control, you may cast it without paying its mana cost. If you don't cast it, put it on the bottom of your library.

March from Velis Vel

Choose a nonbasic land type. Each land you control of that type becomes a copy of target creature you control until end of turn and gains haste until end of turn.
Flashback {4}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Howlpack Alpha

Each other creature you control that's a Werewolf or a Wolf gets +1/+1.
At the beginning of your end step, create a 2/2 green Wolf creature token.
At the beginning of each upkeep, if a player cast two or more spells last turn, transform Howlpack Alpha.

Mayor of Avabruck

Other Human creatures you control get +1/+1.
At the beginning of each upkeep, if no spells were cast last turn, transform Mayor of Avabruck.

Mayor of Avabruck // Howlpack Alpha

Long River Lurker

Ward {1}
Other Frogs you control have ward {1}.
When Long River Lurker enters, target creature you control can't be blocked this turn. Whenever that creature deals combat damage this turn, you may exile it. If you do, return it to the battlefield under its owner's control.

Sage of the Maze

{T}: Add two mana in any combination of colors.
{T}: Until end of turn, target land you control becomes an X/X Citizen creature with haste in addition to its other types, where X is twice the number of Gates you control. Activate only as a sorcery.
Tap an untapped Gate you control: Untap Sage of the Maze.

Harabaz Druid

{T}: Add X mana of any one color, where X is the number of Allies you control.

Cloudpost

Cloudpost enters tapped.
{T}: Add {C} for each Locus on the battlefield.

Aven Courier

Flying
Whenever Aven Courier attacks, choose a counter on a permanent you control. Put a counter of that kind on target permanent you control if it doesn't have a counter of that kind on it.

Tendershoot Dryad

Ascend (If you control ten or more permanents, you get the city's blessing for the rest of the game.)
At the beginning of each upkeep, create a 1/1 green Saproling creature token.
Saprolings you control get +2/+2 as long as you have the city's blessing.

Elvish Champion

Other Elf creatures get +1/+1 and have forestwalk. (They can't be blocked as long as defending player controls a Forest.)

Vodalian Hexcatcher

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

Have

Heroic Intervention

Permanents you control gain hexproof and indestructible until end of turn.

Lightning Greaves

Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}

Struggle for Project Purity

As Struggle for Project Purity enters, choose Brotherhood or Enclave.
• Brotherhood — At the beginning of your upkeep, each opponent draws a card. You draw a card for each card drawn this way.
• Enclave — Whenever a player attacks you with one or more creatures, that player gets twice that many rad counters.

Malcolm, Keen-Eyed Navigator

Flying
Whenever one or more Pirates you control deal damage to your opponents, you create a Treasure token for each opponent dealt damage. (It's an artifact with "{T}, Sacrifice this artifact: Add one mana of any color.")
Partner (You can have two commanders if both have partner.)

Venom Sliver

Sliver creatures you control have deathtouch. (Any amount of damage a creature with deathtouch deals to a creature is enough to destroy it.)

Rapid Hybridization

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

Gemhide Sliver

All Slivers have "{T}: Add one mana of any color."

Multiclass Baldric

Equipped creature has lifelink if you control a Cleric, deathtouch if you control a Rogue, haste if you control a Warrior, and flying if you control a Wizard.
As long as you have a full party, prevent all damage that would be dealt to equipped creature.
Equip {2}

Shifting Sliver

Slivers can't be blocked except by Slivers.

Island

Eagle Vision

Freerunning {1}{U} (You may cast this spell for its freerunning cost if you dealt combat damage to a player this turn with an Assassin or commander.)
Draw three cards.

Command Tower

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

Overlord of the Hauntwoods

Impending 4—{1}{G}{G} (If you cast this spell for its impending cost, it enters with four time counters and isn't a creature until the last is removed. At the beginning of your end step, remove a time counter from it.)
Whenever Overlord of the Hauntwoods enters or attacks, create a tapped colorless land token named Everywhere that is every basic land type.

Megantic Sliver

Nature's Claim

Destroy target artifact or enchantment. Its controller gains 4 life.

Galerider Sliver

Sliver creatures you control have flying.

Manaweft Sliver

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

Winged Sliver

Rampant Frogantua

Trample
Rampant Frogantua gets +10/+10 for each player who has lost the game.
Whenever Rampant Frogantua deals combat damage to a player, you may mill that many cards. Put any number of land cards from among them onto the battlefield tapped.

Seafloor Oracle

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

Concerted Defense

Counter target noncreature spell unless its controller pays {1} plus an additional {1} for each creature in your party. (Your party consists of up to one each of Cleric, Rogue, Warrior, and Wizard.)

Urza's Power Plant

{T}: Add {C}. If you control an Urza's Mine and an Urza's Tower, add {C}{C} instead.

Seshiro the Anointed

Other Snake creatures you control get +2/+2.
Whenever a Snake you control deals combat damage to a player, you may draw a card.

Negate

Collective Restraint

Domain — Creatures can't attack you unless their controller pays {X} for each creature they control that's attacking you, where X is the number of basic land types among lands you control.

Scion of Oona

Flash
Flying
Other Faerie creatures you control get +1/+1.
Other Faeries you control have shroud. (They can't be the targets of spells or abilities.)

Baldur's Gate

{T}: Add {C}.
{2}, {T}: Add X mana of any one color, where X is the number of other Gates you control.

Hakbal of the Surging Soul

At the beginning of combat on your turn, each Merfolk creature you control 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 the exploring creature, then put the card back or put it into your graveyard.)
Whenever Hakbal of the Surging Soul attacks, you may put a land card from your hand onto the battlefield. If you don't, draw a card.

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.

Teferi's Time Twist

Exile target permanent you control. Return that card to the battlefield under its owner's control at the beginning of the next end step. If it enters as a creature, it enters with an additional +1/+1 counter on it.

Simic Signet

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.

Yavimaya Coast

{T}: Add {C}.
{T}: Add {G} or {U}. Yavimaya Coast deals 1 damage to you.

Mirage Mirror

{2}: Mirage Mirror becomes a copy of target artifact, creature, enchantment, or land until end of turn.

Sachi, Daughter of Seshiro

Other Snake creatures you control get +0/+1.
Shamans you control have "{T}: Add {G}{G}."

Return to Nature

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

Don't Have

Timber Protector

Other Treefolk creatures you control get +1/+1.
Other Treefolk and Forests you control have indestructible.

Three Visits

Search your library for a Forest card, put it onto the battlefield, then shuffle.

Beast Within

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

Synapse Sliver

Whenever a Sliver deals combat damage to a player, its controller may draw a card.

Finale of Revelation

Draw X cards. If X is 10 or more, instead shuffle your graveyard into your library, draw X cards, untap up to five lands, and you have no maximum hand size for the rest of the game.
Exile Finale of Revelation.

Feline Sovereign

Other Cats you control get +1/+1 and have protection from Dogs.
Whenever one or more Cats you control deal combat damage to a player, destroy up to one target artifact or enchantment that player controls.

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.)

Blossoming Defense

Target creature you control gets +2/+2 and gains hexproof until end of turn.

Cyclone Summoner

When Cyclone Summoner enters, if you cast it from your hand, return all permanents to their owners' hands except for Giants, Wizards, and lands.

Crop Rotation

As an additional cost to cast this spell, sacrifice a land.
Search your library for a land card, put that card onto the battlefield, then shuffle.

Swarmyard

{T}: Add {C}.
{T}: Regenerate target Insect, Rat, Spider, or Squirrel. (The next time it would be destroyed this turn, instead tap it, remove it from combat, and heal all damage on it.)

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.)

Dazzling Denial

Counter target spell unless its controller pays {2}. If you control a Bird, counter that spell unless its controller pays {4} instead.

Mass Appeal

Flooded Grove

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

Omo, Queen of Vesuva

Whenever Omo, Queen of Vesuva enters or attacks, put an everything counter on each of up to one target land and up to one target creature.
Each land with an everything counter on it is every land type in addition to its other types.
Each nonland creature with an everything counter on it is every creature type.

Priest of Titania

{T}: Add {G} for each Elf on the battlefield.

Hour of Promise

Search your library for up to two land cards, put them onto the battlefield tapped, then shuffle. Then if you control three or more Deserts, create two 2/2 black Zombie creature tokens.

Fellwar Stone

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

Whelming Wave

Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.

Azami, Lady of Scrolls

Tap an untapped Wizard you control: Draw a card.

Forest

Glimmerpost

When Glimmerpost enters, you gain 1 life for each Locus on the battlefield.
{T}: Add {C}.

Supreme Phantom

Flying
Other Spirits you control get +1/+1.

Overflowing Basin

Urza's Tower

{T}: Add {C}. If you control an Urza's Mine and an Urza's Power-Plant, add {C}{C}{C} instead.

Myr Galvanizer

Other Myr creatures you control get +1/+1.
{1}, {T}: Untap each other Myr you control.

Pongify

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

Arcane Signet

Enduring Curiosity

Flash
Whenever a creature you control deals combat damage to a player, draw a card.
When Enduring Curiosity dies, if it was a creature, return it to the battlefield under its owner's control. It's an enchantment. (It's not a creature.)

Curious Altisaur

Vigilance, reach
Whenever a Dinosaur you control deals combat damage to a player, draw a card.

Distant Melody

Choose a creature type. Draw a card for each permanent you control of that type.

Greatbow Doyen

Other Archer creatures you control get +1/+1.
Whenever an Archer you control deals damage to a creature, that Archer deals that much damage to that creature's controller.

Arbor Elf

Elvish Archdruid

Other Elf creatures you control get +1/+1.
{T}: Add {G} for each Elf you control.

Sosuke, Son of Seshiro

Other Snake creatures you control get +1/+0.
Whenever a Warrior you control deals combat damage to a creature, destroy that creature at end of combat.

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}.

Sol Ring

Masked Vandal

Changeling (This card is every creature type.)
When Masked Vandal enters, you may exile a creature card from your graveyard. If you do, exile target artifact or enchantment an opponent controls.

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}.)

Shapesharer

Changeling (This card is every creature type.)
{2}{U}: Target Shapeshifter becomes a copy of target creature until your next turn.

Urza's Mine

{T}: Add {C}. If you control an Urza's Power-Plant and an Urza's Tower, add {C}{C} instead.

Biowaste Blob

Oozes you control get +1/+1.
At the beginning of your upkeep, if you control a commander, create a token that's a copy of Biowaste Blob.

Nature's Lore

Search your library for a Forest card, put that card onto the battlefield, then shuffle.

Sea Gate Loremaster

{T}: Draw a card for each Ally you control.

Rogue's Passage

{T}: Add {C}.
{4}, {T}: Target creature can't be blocked this turn.

Evasive Action

Domain — Counter target spell unless its controller pays {1} for each basic land type among lands you control.

Guardian Project

Whenever a nontoken creature you control enters, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

Basilisk Gate

{T}: Add {C}.
{2}, {T}: Target creature gets +X/+X until end of turn, where X is the number of Gates you control. Activate only as a sorcery.

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.

Maskwood Nexus

Creatures you control are every creature type. The same is true for creature spells you control and creature cards you own that aren't on the battlefield.
{3}, {T}: Create a 2/2 blue Shapeshifter creature token with changeling. (It is every creature type.)

Talisman of Curiosity

{T}: Add {C}.
{T}: Add {G} or {U}. Talisman of Curiosity deals 1 damage to you.