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.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Whenever Cold-Eyed Selkie deals combat damage to a player, you may draw that many cards.

Choose a permanent type. Return all cards of the chosen type from your graveyard to your hand. Flashback {5}{G}{G} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Whenever Fallowsage becomes tapped, you may draw a card.

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.

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.

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

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

Destroy target artifact, enchantment, or creature with flying.

Sacrifice Cursecatcher: Counter target instant or sorcery spell unless its controller pays {1}.

Return target nonland permanent you don't control to its owner's hand. Overload {6}{U} (You may cast this spell for its overload cost. If you do, change "target" in its text to "each.")

{U}{U}, {T}: Gain control of target legendary permanent. (This effect lasts indefinitely.)

Return all noncreature, nonland permanents to their owners' hands.

Return all nonblue creatures to their owners' hands.

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

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

Return all nonland permanents target player controls to their owner's hand.

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

Blue creatures you control can't be blocked.

Tap an untapped Merfolk you control: Target player mills a card.

You may look at the top card of your library any time. You may cast Merfolk spells from the top of your library. Whenever you cast a Merfolk spell, you may pay {1}. If you do, create a 1/1 blue Merfolk creature token.

Whenever Grimoire Thief becomes tapped, exile the top three cards of target opponent's library face down. You may look at cards exiled with Grimoire Thief. {U}, Sacrifice Grimoire Thief: Turn all cards exiled with Grimoire Thief face up. Counter all spells with those names.

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.)

Sacrifice Mistcaller: Until end of turn, if a nontoken creature would enter the battlefield and it wasn't cast, exile it instead.

{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.

{1}{U}, Tap two untapped Wizards you control: Copy target instant or sorcery spell. You may choose new targets for the copy.

Islandwalk (This creature can't be blocked as long as defending player controls an Island.) Whenever Thada Adel, Acquisitor 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.

Kicker {X}. X can't be 0. (You may pay an additional {X} as you cast this spell.) Flying When Thieving Skydiver enters the battlefield, if it was kicked, gain control of target artifact with mana value X or less. If that artifact is an Equipment, attach it to Thieving Skydiver.

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.

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

Whenever a permanent you control becomes untapped, Wake Thrasher gets +1/+1 until end of turn.

Whenever one or more nontoken Merfolk you control become tapped, create a 1/1 blue Merfolk creature token with hexproof.

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.)

Flash When Lost in the Maze enters the battlefield, tap X target creatures. Put a stun counter on each of those creatures you don't control. (If a permanent with a stun counter would become untapped, remove one from it instead.) Tapped creatures you control have hexproof.

({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.

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

Dreamroot Cascade enters the battlefield tapped unless you control two or more other lands. {T}: Add {G} or {U}.

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

({T}: Add {G}.)

Hinterland Harbor enters the battlefield tapped unless you control a Forest or an Island. {T}: Add {G} or {U}.

({T}: Add {U}.)

Path of Ancestry enters the battlefield 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.)

Rejuvenating Springs enters the battlefield tapped unless you have two or more opponents. {T}: Add {G} or {U}.

You have no maximum hand size. {T}: Add {C}.

Simic Growth Chamber enters the battlefield tapped. When Simic Growth Chamber enters the battlefield, return a land you control to its owner's hand. {T}: Add {G}{U}.

({T}: Add {G} or {U}.) Tangled Islet enters the battlefield tapped.

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.

As Vineglimmer Snarl enters the battlefield, you may reveal a Forest or Island card from your hand. If you don't, Vineglimmer Snarl enters the battlefield tapped. {T}: Add {G} or {U}.

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.

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}.)

Each creature gets +1/+1 for each other creature on the battlefield that shares at least one creature type with it. (For example, if two Goblin Warriors and a Goblin Shaman are on the battlefield, each gets +2/+2.)

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

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

Other Merfolk you control get +1/+1.

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

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

Until end of turn, creatures you control gain trample and get +X/+X, where X is the greatest power among creatures you control.

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.

Search your library for a Plains, Island, Swamp, or Mountain card, put it onto the battlefield tapped, then shuffle.

Search your library for up to X basic land cards, where X is the number of tapped creatures you control, put those cards onto the battlefield tapped, then shuffle.

As Heraldic Banner enters the battlefield, choose a color. Creatures you control of the chosen color get +1/+0. {T}: Add one mana of the chosen color.

Search your library for a basic land card, put that card onto the battlefield tapped, then shuffle.

{T}: Add {C}{C}.

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.

Enchant player Whenever enchanted player is attacked, untap all nonland permanents you control. Each opponent attacking that player untaps all nonland permanents they control.

Creatures don't untap during their controllers' untap steps. Whenever a creature enters the battlefield, untap all creatures.

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

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.

As Kindred Discovery enters the battlefield, choose a creature type. Whenever a creature you control of the chosen type enters the battlefield or attacks, draw a card.