Destroy target creature. It can't be regenerated. Its controller creates a 1/1 white Spirit creature token with flying.
{3}{U}
Aquatic Incursion
Enchantment
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.
--
Ash Barrens
Land
{T}: Add {C}.
Basic landcycling {1} ({1}, Discard this card: Search your library for a basic land card, reveal it, put it into your hand, then shuffle.)
--
Azorius Chancery
Land
Azorius Chancery enters the battlefield tapped.
When Azorius Chancery enters the battlefield, return a land you control to its owner's hand.
{T}: Add {W}{U}.
{3}
Azorius Cluestone
Artifact
{T}: Add {W} or {U}.
{W}{U}, {T}, Sacrifice Azorius Cluestone: Draw a card.
{3}
Azorius Keyrune
Artifact
{T}: Add {W} or {U}.
{W}{U}: Azorius Keyrune becomes a 2/2 white and blue Bird artifact creature with flying until end of turn.
{3}
Azorius Locket
Artifact
{T}: Add {W} or {U}.
{W/U}{W/U}{W/U}{W/U}, {T}, Sacrifice Azorius Locket: Draw two cards.
{2}
Azorius Signet
Artifact
{1}, {T}: Add {W}{U}.
{3}
Burnished Hart
Artifact Creature - Elk
{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.
2 /
2
{1}{W}{W}
Citywide Bust
Sorcery
Destroy all creatures with toughness 4 or greater.
--
Command Tower
Land
{T}: Add one mana of any color in your commander's color identity.
{3}
Commander's Sphere
Artifact
{T}: Add one mana of any color in your commander's color identity.
Sacrifice Commander's Sphere: Draw a card.
{2}{W}
Crib Swap
Tribal Instant - Shapeshifter
Changeling (This card is every creature type.)
Exile target creature. Its controller creates a 1/1 colorless Shapeshifter creature token with changeling.
{5}{U}
Deepchannel Mentor
Creature - Merfolk Rogue
Blue creatures you control can't be blocked.
2 /
2
{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}{W}
Disenchant
Instant
Destroy target artifact or enchantment.
{X}{U}{U}
Displacement Wave
Sorcery
Return all nonland permanents with mana value X or less to their owners' hands.
{W}{U}
Dovin's Veto
Instant
This spell can't be countered.
Counter target noncreature spell.
{2}{U}
Drowner of Secrets
Creature - Merfolk Wizard
Tap an untapped Merfolk you control: Target player mills a card.
1 /
3
{3}{U}
Fallowsage
Creature - Merfolk Wizard
Whenever Fallowsage becomes tapped, you may draw a card.
2 /
2
--
Flood Plain
Land
Flood Plain enters the battlefield tapped.
{T}, Sacrifice Flood Plain: Search your library for a Plains or Island card, put it onto the battlefield, then shuffle.
{3}{U}
Frozen Aether
Enchantment
Artifacts, creatures, and lands your opponents control enter the battlefield tapped.
{2}{W}
Harpoon Sniper
Creature - Merfolk Archer
{W}, {T}: Harpoon Sniper deals X damage to target attacking or blocking creature, where X is the number of Merfolk you control.
2 /
2
{4}
Hedron Archive
Artifact
{T}: Add {C}{C}.
{2}, {T}, Sacrifice Hedron Archive: Draw two cards.
--
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}.)
--
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}{W}
Judge of Currents
Creature - Merfolk Wizard
Whenever a Merfolk you control becomes tapped, you may gain 1 life.
1 /
1
{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
--
Lonely Sandbar
Land
Lonely Sandbar enters the battlefield tapped.
{T}: Add {U}.
Cycling {U} ({U}, Discard this card: Draw a card.)
{2}{W}{W}
Martial Law
Enchantment
At the beginning of your upkeep, detain target creature an opponent controls. (Until your next turn, that creature can't attack or block and its activated abilities can't be activated.)
--
Memorial to Genius
Land
Memorial to Genius enters the battlefield tapped.
{T}: Add {U}.
{4}{U}, {T}, Sacrifice Memorial to Genius: Draw two cards.
{1}{U}
Merfolk Looter
Creature - Merfolk Rogue
{T}: Draw a card, then discard a card.
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
{U}{U}
Merfolk Trickster
Creature - Merfolk Wizard
Flash
When Merfolk Trickster enters the battlefield, tap target creature an opponent controls. It loses all abilities until end of turn.
2 /
2
{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
{1}{U}
Military Intelligence
Enchantment
Whenever you attack with two or more creatures, draw a card.
{2}
Mirror Shield
Artifact - Equipment
Equipped creature gets +0/+2 and has hexproof and "Whenever a creature with deathtouch blocks or becomes blocked by this creature, destroy that creature."
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)
{3}
Ojutai Monument
Artifact
{T}: Add {W} or {U}.
{4}{W}{U}: Ojutai Monument becomes a 4/4 white and blue Dragon artifact creature with flying until end of turn.
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Plains
Basic Land - Plains
({T}: Add {W}.)
--
Prairie Stream
Land - Plains Island
({T}: Add {W} or {U}.)
Prairie Stream enters the battlefield tapped unless you control two or more basic lands.
{2}
Prismatic Lens
Artifact
{T}: Add {C}.
{1}, {T}: Add one mana of any color.
{1}{U}
Reality Shift
Instant
Exile target creature. Its controller manifests the top card of their library. (That player puts the top card of their library onto the battlefield face down as a 2/2 creature. If it's a creature card, it can be turned face up any time for its mana cost.)
{2}{U}{U}
Reconnaissance Mission
Enchantment
Whenever a creature you control deals combat damage to a player, you may draw a card.
Cycling {2} ({2}, Discard this card: Draw a card.)
--
Remote Isle
Land
Remote Isle enters the battlefield tapped.
{T}: Add {U}.
Cycling {2} ({2}, Discard this card: Draw a card.)
{1}{U}
River Sneak
Creature - Merfolk Warrior
River Sneak can't be blocked.
Whenever another Merfolk enters the battlefield under your control, River Sneak gets +1/+1 until end of turn.
1 /
1
{2}{U}
Sage's Dousing
Tribal Instant - Wizard
Counter target spell unless its controller pays {3}. If you control a Wizard, draw a card.
{3}{U}
Saltwater Stalwart
Creature - Merfolk Warrior
Whenever Saltwater Stalwart deals damage to an opponent, target player draws a card.
2 /
4
{2}{U}
Scroll Thief
Creature - Merfolk Rogue
Whenever Scroll Thief deals combat damage to a player, draw a card.
1 /
3
{1}{U}
Sea Scryer
Creature - Merfolk Wizard
{T}: Add {C}.
{1}, {T}: Add {U}.
1 /
1
{2}{U}{U}
Seafloor Oracle
Creature - Merfolk Wizard
Whenever a Merfolk you control deals combat damage to a player, draw a card.
2 /
3
{1}{U}{U}
Seasinger
Creature - Merfolk
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.
0 /
1
--
Secluded Steppe
Land
Secluded Steppe enters the battlefield tapped.
{T}: Add {W}.
Cycling {W} ({W}, Discard this card: Draw a card.)
--
Sejiri Refuge
Land
Sejiri Refuge enters the battlefield tapped.
When Sejiri Refuge enters the battlefield, you gain 1 life.
{T}: Add {W} or {U}.
{1}{U}
Silvergill Douser
Creature - Merfolk Wizard
{T}: Target creature gets -X/-0 until end of turn, where X is the number of Merfolk and/or Faeries you control.
1 /
1
{1}
Springleaf Drum
Artifact
{T}, Tap an untapped creature you control: Add one mana of any color.
{3}
Staff of the Mind Magus
Artifact
Whenever you cast a blue spell or an Island enters the battlefield under your control, you gain 1 life.
{W}{U}
Staggering Insight
Enchantment - Aura
Enchant creature
Enchanted creature gets +1/+1 and has lifelink and "Whenever this creature deals combat damage to a player, draw a card."
{1}{U}
Stonybrook Angler
Creature - Merfolk Wizard
{1}{U}, {T}: You may tap or untap target creature.
1 /
2
{1}{U}
Stonybrook Banneret
Creature - Merfolk Wizard
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.
1 /
1
{2}{W}
Stonybrook Schoolmaster
Creature - Merfolk Wizard
Whenever Stonybrook Schoolmaster becomes tapped, you may create a 1/1 blue Merfolk Wizard creature token.
1 /
2
{5}{U}{U}{U}
Stormtide Leviathan
Creature - Leviathan
Islandwalk (This creature can't be blocked as long as defending player controls an Island.)
All lands are Islands in addition to their other types.
Creatures without flying or islandwalk can't attack.
8 /
8
{1}{U}{U}
Streambed Aquitects
Creature - Merfolk Scout
{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.
2 /
3
{3}{W}
Summon the School
Tribal Sorcery - Merfolk
Create two 1/1 blue Merfolk Wizard creature tokens.
Tap four untapped Merfolk you control: Return Summon the School from your graveyard to your hand.
{W}
Swords to Plowshares
Instant
Exile target creature. Its controller gains life equal to its power.
{W}{U}
Sygg, River Guide
Legendary Creature - Merfolk Wizard
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.
2 /
2
{2}{U}{U}
Tempest Caller
Creature - Merfolk Wizard
When Tempest Caller enters the battlefield, tap all creatures target opponent controls.
2 /
3
--
Temple of Enlightenment
Land
Temple of Enlightenment enters the battlefield tapped.
When Temple of Enlightenment enters the battlefield, scry 1.
{T}: Add {W} or {U}.
{U}
Tidal Warrior
Creature - Merfolk Warrior
{T}: Target land becomes an Island until end of turn.
1 /
1
{U}
Tideshaper Mystic
Creature - Merfolk Wizard
{T}: Target land becomes the basic land type of your choice until end of turn. Activate only during your turn.
1 /
1
--
Tranquil Cove
Land
Tranquil Cove enters the battlefield tapped.
When Tranquil Cove enters the battlefield, you gain 1 life.
{T}: Add {W} or {U}.
--
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.
{3}{W}
Veteran of the Depths
Creature - Merfolk Soldier
Whenever Veteran of the Depths becomes tapped, you may put a +1/+1 counter on it.
2 /
2
{2}{U}
Wake Thrasher
Creature - Merfolk Soldier
Whenever a permanent you control becomes untapped, Wake Thrasher gets +1/+1 until end of turn.
1 /
1
{3}{U}{U}
Waterspout Weavers
Creature - Merfolk Wizard
Kinship -- At the beginning of your upkeep, you may look at the top card of your library. If it shares a creature type with Waterspout Weavers, you may reveal it. If you do, each creature you control gains flying until end of turn.
3 /
3
{4}{W}
Wellgabber Apothecary
Creature - Merfolk Cleric
{1}{W}: Prevent all damage that would be dealt to target tapped Merfolk or Kithkin creature this turn.
2 /
3
{2}{U}{U}
Whelming Wave
Sorcery
Return all creatures to their owners' hands except for Krakens, Leviathans, Octopuses, and Serpents.
{3}
Whispersilk Cloak
Artifact - Equipment
Equipped creature can't be blocked and has shroud. (It can't be the target of spells or abilities.)
Equip {2}
{1}{U}{U}
Wizard's Retort
Instant
This spell costs {1} less to cast if you control a Wizard.