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 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.

Whenever you cast a blue spell, Gravelgill Duo gets +1/+1 until end of turn. Whenever you cast a black spell, Gravelgill Duo gains fear until end of turn. (It can't be blocked except by artifact creatures and/or black creatures.)

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

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.

You draw two cards and you lose 2 life.

Surveil 2, then draw two cards. Notion Rain deals 2 damage to you. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

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

Tap another untapped Rogue you control: Sure-Footed Infiltrator can't be blocked this turn. Whenever Sure-Footed Infiltrator deals combat damage to a player, draw a card.

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}.)

Changeling (This card is every creature type.) Changeling Outcast can't block and can't be blocked.

Inkfathom Infiltrator can't block and can't be blocked.

Fear (This creature can't be blocked except by artifact creatures and/or black creatures.) {2}{U}{B}: Each unblocked creature has base power and toughness 4/1 until end of turn.

Mist-Cloaked Herald can't be blocked.

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}{U}: Adapt 1. (If this creature has no +1/+1 counters on it, put a +1/+1 counter on it.) Whenever one or more +1/+1 counters are put on Benthic Biomancer, draw a card, then discard a card.

Whenever a player casts a blue spell, you may pay {1}. If you do, target player mills two cards.

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

Level up {1}{U} ({1}{U}: Put a level counter on this. Level up only as a sorcery.) LEVEL 1-2 0/1 {T}: Draw a card, then discard a card. LEVEL 3+ 0/1 {T}: Draw a card.

{T}: Draw a card, then discard a card.

{U}, {T}: Target player mills two cards.

When Merfolk Pupil enters the battlefield, draw a card, then discard a card. {1}{U}, Exile Merfolk Pupil from your graveyard: Draw a card, then discard a card.

When Merrow Witsniper enters the battlefield, target player mills a card.

Deathtouch When Mire Triton enters the battlefield, mill two cards and you gain 2 life.

Whenever Sage of the Falls or another non-Human creature enters the battlefield under your control, you may draw a card. If you do, discard a card.

{1}{U}, {T}: Draw a card, then discard a card.

Whenever Towering-Wave Mystic deals damage, target player mills that many cards.

{T}: Draw a card, then discard a card. If you discarded an instant or sorcery card this way, each opponent loses 1 life and you gain 1 life. {2}, Sacrifice Vohar, Vodalian Desecrator: You may cast target instant or sorcery card from your graveyard this turn. If that spell would be put into your graveyard, exile it instead. Activate only as a sorcery.

Bojuka Bog enters the battlefield tapped. When Bojuka Bog enters the battlefield, exile target player's graveyard. {T}: Add {B}.

As Choked Estuary enters the battlefield, you may reveal an Island or Swamp card from your hand. If you don't, Choked Estuary enters the battlefield tapped. {T}: Add {U} or {B}.

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

{1}, {T}: Add {U}{B}.

Dimir Aqueduct enters the battlefield tapped. When Dimir Aqueduct enters the battlefield, return a land you control to its owner's hand. {T}: Add {U}{B}.

{T}: Add {C}. {2}, {T}: Each player draws a card, then discards a card.

({T}: Add {U}.)

Memorial to Folly enters the battlefield tapped. {T}: Add {B}. {2}{B}, {T}, Sacrifice Memorial to Folly: Return target creature card from your graveyard to your hand.

Myriad Landscape enters the battlefield tapped. {T}: Add {C}. {2}, {T}, Sacrifice Myriad Landscape: Search your library for up to two basic land cards that share a land type, put them onto the battlefield tapped, then shuffle.

{T}: Add {U}. If you played a land this turn, add {B} instead.

Shipwreck Marsh enters the battlefield tapped unless you control two or more other lands. {T}: Add {U} or {B}.

({T}: Add {U} or {B}.) Sunken Hollow enters the battlefield tapped unless you control two or more basic lands.

({T}: Add {B}.)

{T}: Add {C}. {T}: Add {U} or {B}. Activate only if you control a Swamp.

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

{1}, {T}: Add {U}{B}.

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

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.

{T}: Add {C}. {1}, {T}, Sacrifice Mind Stone: Draw a card.

{2}, {T}, Sacrifice Navigation Orb: Search your library for up to two basic land cards and/or Gate cards, reveal those cards, put one onto the battlefield tapped and the other into your hand, 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.

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

{T}, Exile cards from your graveyard equal to the number of opponents you have: Target creature card in your graveyard gains encore until end of turn. The encore cost is equal to its mana cost. (Exile the creature card and pay its mana cost: 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.)

Return up to two target creature cards with total mana value 3 or less from your graveyard to the battlefield. Put a deathtouch counter on either of them. Then put a menace counter on either of them.

This spell costs {1} less to cast for each artifact you control. When Emry, Lurker of the Loch enters the battlefield, mill four cards. {T}: Choose target artifact card in your graveyard. You may cast that card this turn. (You still pay its costs. Timing rules still apply.)

Choose a creature type. Return up to two creature cards of that type from your graveyard to the battlefield. If this spell was foretold, return all creature cards of that type from your graveyard to the battlefield instead. Foretell {5}{B}{B} (During your turn, you may pay {2} and exile this card from your hand face down. Cast it on a later turn for its foretell cost.)

Surveil 2, then choose an instant or sorcery card in your graveyard. You may cast it this turn. If that spell would be put into your graveyard, exile it instead. (To surveil 2, look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Each player chooses a creature type. Each player returns all creature cards of a type chosen this way from their graveyard to the battlefield.

Choose one or both — • Counter target creature spell. • Return target creature card from your graveyard to your hand.

Return target creature card with mana value 3 or less from your graveyard to the battlefield. Cycling {2} ({2}, Discard this card: Draw a card.)

You may pay {1}{B} rather than pay this spell's mana cost. If the {1}{B} cost was paid, an opponent draws a card. Exile target creature or planeswalker.

Return target permanent to its owner's hand. Its controller loses 3 life. Transmute {1}{U}{B} ({1}{U}{B}, Discard this card: Search your library for a card with the same mana value as this card, reveal it, put it into your hand, then shuffle. Transmute only as a sorcery.)

Choose one — • Counter target spell with mana value less than or equal to the number of cards in its controller's graveyard. • Destroy target creature with mana value less than or equal to the number of cards in its controller's graveyard.

This spell costs {2} less to cast if it targets an attacking creature. Return target creature to its owner's hand. Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Choose a creature type. Destroy all creatures that aren't of the chosen type.

This spell costs {1} less to cast for each creature card in your graveyard. Exile target creature or planeswalker.

Convoke (Your creatures can help cast this spell. Each creature you tap while casting this spell pays for {1} or one mana of that creature's color.) Destroy target creature or planeswalker. Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

This spell costs {2} less to cast if it targets a legendary creature. Destroy target creature. Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

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

Choose one — • Destroy target creature with mana value 3 or less. • Return target creature to its owner's hand.

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.

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.

Whenever a spell or ability you control counters a spell, you may create a 1/1 blue Merfolk creature token. Tap seven untapped Merfolk you control: Counter target spell.

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.

{3}: Target player mills three cards.

Counter target spell. Its controller may draw up to two cards at the beginning of the next turn's upkeep. You draw a card at the beginning of the next turn's upkeep.

Each player mills ten cards. For each player, choose a creature or planeswalker card in that player's graveyard. Put those cards onto the battlefield under your control. Then each creature you control becomes a Phyrexian in addition to its other types.

Surveil 1. (Look at the top card of your library. You may put it into your graveyard.) Draw a card.

Surveil 5. (Look at the top five cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.)

Surveil 2. (Look at the top two cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.) Draw a card.

Each player mills two cards. Then you put a creature card from a graveyard onto the battlefield under your control.

Destroy target creature. You lose 2 life.

{T}: Add {B}. {1}{B}{B}, {T}, Sacrifice Infernal Idol: You draw two cards and you lose 2 life.

Delve (Each card you exile from your graveyard while casting this spell pays for {1}.) Destroy target creature.

Counter target noncreature spell.

Surveil 3. (Look at the top three cards of your library, then put any number of them into your graveyard and the rest on top of your library in any order.) Flashback {1}{U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Whenever Saltwater Stalwart deals damage to an opponent, target player draws a card.

Whenever Scroll Thief deals combat damage to a player, draw a card.

When Solemn Simulacrum enters the battlefield, you may search your library for a basic land card, put that card onto the battlefield tapped, then shuffle. When Solemn Simulacrum dies, you may draw a card.