When Aquatic Incursion enters the battlefield, create two 1/1 blue Merfolk creature tokens with hexproof. (They can't be the targets of spells or abilities your opponents control.)
{3}{U}: Target Merfolk can't be blocked this turn.
{U}
Aquitect's Will
Tribal Sorcery - Merfolk
Put a flood counter on target land. That land is an Island in addition to its other types for as long as it has a flood counter on it. If you control a Merfolk, draw a card.
{2}{G}
Beast Within
Instant
Destroy target permanent. Its controller creates a 3/3 green Beast creature token.
--
Blast Zone
Land
Blast Zone enters the battlefield with a charge counter on it.
{T}: Add {C}.
{X}{X}, {T}: Put X charge counters on Blast Zone.
{3}, {T}, Sacrifice Blast Zone: Destroy each nonland permanent with mana value equal to the number of charge counters on Blast Zone.
--
Blighted Cataract
Land
{T}: Add {C}.
{5}{U}, {T}, Sacrifice Blighted Cataract: Draw two cards.
--
Botanical Sanctum
Land
Botanical Sanctum enters the battlefield tapped unless you control two or fewer other lands.
{T}: Add {G} or {U}.
{U}
Brainstorm
Instant
Draw three cards, then put two cards from your hand on top of your library in any order.
--
Breeding Pool
Land - Forest Island
({T}: Add {G} or {U}.)
As Breeding Pool enters the battlefield, you may pay 2 life. If you don't, it enters the battlefield tapped.
--
Cave of Temptation
Land
{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{4}, {T}, Sacrifice Cave of Temptation: Put two +1/+1 counters on target creature. Activate only as a sorcery.
{U}{U}
Counterspell
Instant
Counter target spell.
{5}{G}{G}{G}
Craterhoof Behemoth
Creature - Beast
Haste
When Craterhoof Behemoth enters the battlefield, creatures you control gain trample and get +X/+X until end of turn, where X is the number of creatures you control.
5 /
5
{1}{G}
Cryptolith Rite
Enchantment
Creatures you control have "{T}: Add one mana of any color."
{2}{G}
Cultivate
Sorcery
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.
{1}{G}
Deeproot Champion
Creature - Merfolk Shaman
Whenever you cast a noncreature spell, put a +1/+1 counter on Deeproot Champion.
1 /
1
{1}{G}
Deeproot Elite
Creature - Merfolk Warrior
Whenever another Merfolk enters the battlefield under your control, put a +1/+1 counter on target Merfolk you control.
1 /
1
{2}{U}
Deeproot Waters
Enchantment
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.)
{1}{U}{U}
Disallow
Instant
Counter target spell, activated ability, or triggered ability. (Mana abilities can't be targeted.)
{1}{U}{U}
Dissipate
Instant
Counter target spell. If that spell is countered this way, exile it instead of putting it into its owner's graveyard.
{4}
Door of Destinies
Artifact
As Door of Destinies enters the battlefield, choose a creature type.
Whenever you cast a spell of the chosen type, put a charge counter on Door of Destinies.
Creatures you control of the chosen type get +1/+1 for each charge counter on Door of Destinies.
{1}{U}
Dramatic Reversal
Instant
Untap all nonland permanents you control.
{1}{G}{G}
Eternal Witness
Creature - Human Shaman
When Eternal Witness enters the battlefield, you may return target card from your graveyard to your hand.
2 /
1
{2}{G}
Evolution Sage
Creature - Elf Druid
Landfall -- Whenever a land enters the battlefield under your control, proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
3 /
2
--
Evolving Wilds
Land
{T}, Sacrifice Evolving Wilds: Search your library for a basic land card, put it onto the battlefield tapped, then shuffle.
{3}{U}
Fallowsage
Creature - Merfolk Wizard
Whenever Fallowsage becomes tapped, you may draw a card.
2 /
2
{3}{G}
Forerunner of the Heralds
Creature - Merfolk Scout
When Forerunner of the Heralds enters the battlefield, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top.
Whenever another Merfolk enters the battlefield under your control, put a +1/+1 counter on Forerunner of the Heralds.
3 /
2
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Forest
Basic Land - Forest
({T}: Add {G}.)
--
Gateway Plaza
Land - Gate
Gateway Plaza enters the battlefield tapped.
When Gateway Plaza enters the battlefield, sacrifice it unless you pay {1}.
{T}: Add one mana of any color.
{G}{U}
Growth Spiral
Instant
Draw a card. You may put a land card from your hand onto the battlefield.
--
Guildmages' Forum
Land
{T}: Add {C}.
{1}, {T}: Add one mana of any color. If that mana is spent on a multicolored creature spell, that creature enters the battlefield with an additional +1/+1 counter on it.
{1}{G}{U}
Hadana's Climb
Legendary Enchantment
At the beginning of combat on your turn, put a +1/+1 counter on target creature you control. Then if that creature has three or more +1/+1 counters on it, transform Hadana's Climb.
--
Winged Temple of Orazca
Legendary Land
(Transforms from Hadana's Climb.)
{T}: Add one mana of any color.
{1}{G}{U}, {T}: Target creature you control gains flying and gets +X/+X until end of turn, where X is its power.
{3}{U}
Herald of Secret Streams
Creature - Merfolk Warrior
Creatures you control with +1/+1 counters on them can't be blocked.
2 /
3
{1}{G}
Heroic Intervention
Instant
Permanents you control gain hexproof and indestructible until end of turn.
--
Holdout Settlement
Land
{T}: Add {C}. ({C} represents colorless mana.)
{T}, Tap an untapped creature you control: Add one mana of any color.
{G/U}{ // }{1}{G}{U}
Incubation // Incongruity
Sorcery // Instant
Look at the top five cards of your library. You may reveal a creature card from among them and put it into your hand. Put the rest on the bottom of your library in a random order.
Exile target creature. That creature's controller creates a 3/3 green Frog Lizard creature token.
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
--
Island
Basic Land - Island
({T}: Add {U}.)
{1}{G}{G}
Jadelight Ranger
Creature - Merfolk Scout Ranger
When Jadelight Ranger enters the battlefield, it explores, then it explores again. (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 this creature, then put the card back or put it into your graveyard. Then repeat this process.)
2 /
1
--
Karn's Bastion
Land
{T}: Add {C}.
{4}, {T}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
{G}{U}
Kiora's Follower
Creature - Merfolk
{T}: Untap another target permanent.
2 /
2
{1}{U}{U}
Kira, Great Glass-Spinner
Legendary Creature - Spirit
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."
2 /
2
{2}{G}
Kodama's Reach
Sorcery - Arcane
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.
{1}{U}{U}
Kopala, Warden of Waves
Legendary Creature - Merfolk Wizard
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.
2 /
2
{1}{G}{U}
Kumena, Tyrant of Orazca
Legendary Creature - Merfolk Shaman
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.
2 /
4
{3}
Lifecrafter's Bestiary
Artifact
At the beginning of your upkeep, scry 1.
Whenever you cast a creature spell, you may pay {G}. If you do, draw a card.
{2}
Lightning Greaves
Artifact - Equipment
Equipped creature has haste and shroud. (It can't be the target of spells or abilities.)
Equip {0}
--
Lonely Sandbar
Land
Lonely Sandbar enters the battlefield tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)
{U}{U}
Lord of Atlantis
Creature - Merfolk
Other Merfolk get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)
2 /
2
{3}{U}
Master of Waves
Creature - Merfolk Wizard
Protection from red
Elemental creatures you control get +1/+1.
When Master of Waves enters the battlefield, create a number of 1/0 blue Elemental creature tokens equal to your devotion to blue. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)
2 /
1
{U}{U}
Master of the Pearl Trident
Creature - Merfolk
Other Merfolk creatures you control get +1/+1 and have islandwalk. (They can't be blocked as long as defending player controls an Island.)
2 /
2
--
Memorial to Unity
Land
Memorial to Unity enters the battlefield tapped.
{T}: Add {G}.
{2}{G}, {T}, Sacrifice Memorial to Unity: Look at the top five cards of your library. You may reveal a creature card from among them and put it into your hand. Then put the rest on the bottom of your library in a random order.
{1}{U}
Merfolk Looter
Creature - Merfolk Rogue
{T}: Draw a card, then discard a card.
1 /
1
{G}{U}
Merfolk Mistbinder
Creature - Merfolk Shaman
Other Merfolk you control get +1/+1.
2 /
2
{G}{U}
Merfolk Skydiver
Creature - Merfolk Mutant
Flying
When Merfolk Skydiver enters the battlefield, put a +1/+1 counter on target creature you control.
{3}{G}{U}: Proliferate. (Choose any number of permanents and/or players, then give each another counter of each kind already there.)
1 /
1
{1}{U}{U}
Merfolk Sovereign
Creature - Merfolk Noble
Other Merfolk creatures you control get +1/+1.
{T}: Target Merfolk creature can't be blocked this turn.
2 /
2
{1}{U}
Merrow Commerce
Tribal Enchantment - Merfolk
At the beginning of your end step, untap all Merfolk you control.
{3}{U}
Merrow Harbinger
Creature - Merfolk Wizard
Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
When Merrow Harbinger enters the battlefield, you may search your library for a Merfolk card, reveal it, then shuffle and put that card on top.
2 /
3
{2}{U}
Merrow Reejerey
Creature - Merfolk Soldier
Other Merfolk creatures you control get +1/+1.
Whenever you cast a Merfolk spell, you may tap or untap target permanent.
2 /
2
{2}
Metallic Mimic
Artifact Creature - Shapeshifter
As Metallic Mimic enters the battlefield, choose a creature type.
Metallic Mimic is the chosen type in addition to its other types.
Each other creature you control of the chosen type enters the battlefield with an additional +1/+1 counter on it.
2 /
1
{U}
Mist-Cloaked Herald
Creature - Merfolk Warrior
Mist-Cloaked Herald can't be blocked.
1 /
1
--
Mutavault
Land
{T}: Add {C}.
{1}: Mutavault becomes a 2/2 creature with all creature types until end of turn. It's still a land.
{1}{G}
Naturalize
Instant
Destroy target artifact or enchantment.
{1}{U}
Negate
Instant
Counter target noncreature spell.
{G}{U}
Neoform
Sorcery
As an additional cost to cast this spell, sacrifice a creature.
Search your library for a creature card with mana value equal to 1 plus the sacrificed creature's mana value, put that card onto the battlefield with an additional +1/+1 counter on it, then shuffle.
--
Novijen, Heart of Progress
Land
{T}: Add {C}.
{G}{U}, {T}: Put a +1/+1 counter on each creature that entered the battlefield this turn.
--
Nykthos, Shrine to Nyx
Legendary Land
{T}: Add {C}.
{2}, {T}: Choose a color. Add an amount of mana of that color equal to your devotion to that color. (Your devotion to a color is the number of mana symbols of that color in the mana costs of permanents you control.)
--
Painted Bluffs
Land - Desert
{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{U}
Ponder
Sorcery
Look at the top three cards of your library, then put them back in any order. You may shuffle.
Draw a card.
{1}{G}
Rampant Growth
Sorcery
Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.
--
Reliquary Tower
Land
You have no maximum hand size.
{T}: Add {C}.
{3}{U}
Riverwise Augur
Creature - Merfolk Wizard
When Riverwise Augur enters the battlefield, draw three cards, then put two cards from your hand on top of your library in any order.
2 /
2
{2}{U}
Scroll Thief
Creature - Merfolk Rogue
Whenever Scroll Thief deals combat damage to a player, draw a card.
1 /
3
{2}{U}{U}
Seafloor Oracle
Creature - Merfolk Wizard
Whenever a Merfolk you control deals combat damage to a player, draw a card.
2 /
3
{G}{U}
Simic Ascendancy
Enchantment
{1}{G}{U}: Put a +1/+1 counter on target creature you control.
Whenever one or more +1/+1 counters are put on a creature you control, put that many growth counters on Simic Ascendancy.
At the beginning of your upkeep, if Simic Ascendancy has twenty or more growth counters on it, you win the game.
{2}
Simic Signet
Artifact
{1}, {T}: Add {G}{U}.
{1}
Sol Ring
Artifact
{T}: Add {C}{C}.
{1}{G}
Song of Freyalise
Enchantment - Saga
(As this Saga enters and after your draw step, add a lore counter. Sacrifice after III.)
I, II -- Until your next turn, creatures you control gain "{T}: Add one mana of any color."
III -- Put a +1/+1 counter on each creature you control. Those creatures gain vigilance, trample, and indestructible until end of turn.
{2}
Swiftfoot Boots
Artifact - Equipment
Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.)
Equip {1}
{3}{G}{U}
Tatyova, Benthic Druid
Legendary Creature - Merfolk Druid
Landfall -- Whenever a land enters the battlefield under your control, you gain 1 life and draw a card.
3 /
3
--
Thornwood Falls
Land
Thornwood Falls enters the battlefield tapped.
When Thornwood Falls enters the battlefield, you gain 1 life.
{T}: Add {G} or {U}.
{2}
Throne of the God-Pharaoh
Legendary Artifact
At the beginning of your end step, each opponent loses life equal to the number of tapped creatures you control.
{U}
Tidal Warrior
Creature - Merfolk Warrior
{T}: Target land becomes an Island until end of turn.
1 /
1
--
Tranquil Thicket
Land
Tranquil Thicket enters the battlefield tapped.
{T}: Add {G}.
Cycling {G} ({G}, Discard this card: Draw a card.)
--
Treetop Village
Land
Treetop Village enters the battlefield tapped.
{T}: Add {G}.
{1}{G}: Treetop Village becomes a 3/3 green Ape creature with trample until end of turn. It's still a land. (It can deal excess combat damage to the player or planeswalker it's attacking.)
{U}
Triton Shorestalker
Creature - Merfolk Rogue
Triton Shorestalker can't be blocked.
1 /
1
--
Unclaimed Territory
Land
As Unclaimed Territory enters the battlefield, choose a creature type.
{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell of the chosen type.
--
Unknown Shores
Land
{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{5}
Vanquisher's Banner
Artifact
As Vanquisher's Banner enters the battlefield, choose a creature type.
Creatures you control of the chosen type get +1/+1.
Whenever you cast a creature spell of the chosen type, draw a card.
{U}
Vapor Snag
Instant
Return target creature to its owner's hand. Its controller loses 1 life.
{U}
Void Snare
Sorcery
Return target nonland permanent to its owner's hand.
--
Woodland Stream
Land
Woodland Stream enters the battlefield tapped.
{T}: Add {G} or {U}.
{2}{G}{U}
Zegana, Utopian Speaker
Legendary Creature - Merfolk Wizard
When Zegana, Utopian Speaker enters the battlefield, if you control another creature with a +1/+1 counter on it, draw a card.
{4}{G}{U}: Adapt 4. (If this creature has no +1/+1 counters on it, put four +1/+1 counters on it.)
Each creature you control with a +1/+1 counter on it has trample.