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.

Counter target spell unless its controller pays {X}. Clash with an opponent. If you win, that spell's controller mills four cards. (Each clashing player reveals the top card of their library, then puts that card on the top or bottom. A player wins if their card had a higher mana value.)

{T}: Untap another target permanent you control. {T}, Collect evidence 3: Tap target creature you don't control. (To collect evidence 3, exile cards with total mana value 3 or greater from your graveyard.)

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.

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.

Whenever a Merfolk you control becomes tapped, you may gain 1 life.

Flying Other Merfolk you control get +1/+0 and have flying. Encore {5}{U}{U} ({5}{U}{U}, Exile this card from your graveyard: For each opponent, create a token copy that attacks that opponent this turn if able. They gain haste. Sacrifice them at the beginning of the next end step. Activate only as a sorcery.)

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.

At the beginning of your upkeep, target opponent mills three cards, then you draw a card for each land card put into their graveyard this way.

Arctic Flats enters the battlefield tapped. {T}: Add {G} or {W}.

({T}: Add {G} or {W}.) Arctic Treeline enters the battlefield tapped.

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}.

Boreal Shelf enters the battlefield tapped. {T}: Add {W} or {U}.

Botanical Plaza enters the battlefield tapped. {T}: Add {G} or {W}. {2}{G}{W}, {T}, Sacrifice Botanical Plaza: Draw a card.

As Cavern of Souls 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, and that spell can't be countered.

{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 one mana of any color that a land an opponent controls could produce.

({T}: Add {G}.)

({T}: Add {U}.)

({T}: Add {W}.)

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

Restless Anchorage enters the battlefield tapped. {T}: Add {W} or {U}. {1}{W}{U}: Until end of turn, Restless Anchorage becomes a 2/3 white and blue Bird creature with flying. It's still a land. Whenever Restless Anchorage attacks, create a Map token.

Whenever another permanent enters the battlefield under your control, each opponent mills a card.

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

Each opponent mills fourteen cards. Cycling {1}{U} ({1}{U}, Discard this card: Draw a card.) When you cycle Fractured Sanity, each opponent mills four cards.

Kicker {3}{U} Each opponent mills eight cards. If this spell was kicked, instead each opponent mills half their library, rounded up.

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.

If Leyline of Anticipation is in your opening hand, you may begin the game with it on the battlefield. You may cast spells as though they had flash.

If Leyline of Lifeforce is in your opening hand, you may begin the game with it on the battlefield. Creature spells can't be countered.

If Leyline of Sanctity is in your opening hand, you may begin the game with it on the battlefield. You have hexproof. (You can't be the target of spells or abilities your opponents control.)

Prevent all damage that would be dealt to you and creatures you control this turn.

{T}: Untap another target permanent.

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

You may discard a Plains card rather than pay this spell's mana cost. Destroy target artifact or enchantment.

Counter target spell. You gain 3 life.

Choose two — • Destroy all artifacts. • Destroy all enchantments. • Destroy all creatures with mana value 3 or less. • Destroy all creatures with mana value 4 or greater.

Counter target spell.

Destroy target artifact or enchantment.

Counter target spell. Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Return all creatures to their owners' hands.

As an additional cost to cast this spell, return a creature you control to its owner's hand. Counter target spell.

Return all nonland permanents to their owners' hands. If you return four or more nontoken permanents you control this way, you may put a permanent card from your hand onto the battlefield.

Counter target spell that targets you or a permanent you control. Draw a card.

Destroy target artifact or enchantment. You gain 4 life.

When Oblivion Ring enters the battlefield, exile another target nonland permanent. When Oblivion Ring leaves the battlefield, return the exiled card to the battlefield under its owner's control.

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.

Whenever Stonybrook Schoolmaster becomes tapped, you may create a 1/1 blue Merfolk Wizard creature token.

When Brutalizer Exarch enters the battlefield, choose one — • Search your library for a creature card, reveal it, then shuffle and put that card on top. • Put target noncreature permanent on the bottom of its owner's library.

{X}, {T}: Search your library for a creature card with mana value X or less, reveal it, put it into your hand, then shuffle.

Search your library for a creature card, reveal that card, put it into your hand, then shuffle.

As an additional cost to cast this spell, sacrifice a creature. Search your library for a creature card with mana value X or less, where X is 2 plus the sacrificed creature's mana value. Put that card onto the battlefield, then shuffle. Exile Eldritch Evolution.

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.

Search your library for an enchantment card, reveal it, put it into your hand, then shuffle.

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.

Divine Intervention — When Moon-Blessed Cleric enters the battlefield, you may search your library for an enchantment card, reveal it, then shuffle and put that card on top.

Search your library for an instant or sorcery card, reveal it, then shuffle and put that card on top.

Search your library for a sorcery card, reveal it, then shuffle and put that card on top.

{3}, {T}: Search your library for a Merfolk permanent card, put it onto the battlefield, then shuffle.

{T}: Untap target artifact or creature. Morph {U} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up any time for its morph cost.)

{T}: You may tap or untap another target permanent. Unearth {U} ({U}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the next end step or if it would leave the battlefield. Unearth only as a sorcery.)

{3}: Target player mills three cards.

Whenever an opponent casts their second spell each turn, you create a Treasure token.