At the beginning of your upkeep, you may put a charge counter on Aether Vial. {T}: You may put a creature card with mana value equal to the number of charge counters on Aether Vial from your hand onto the battlefield.

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

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

This spell costs {X} less to cast, where X is the greatest power among creatures you control. {T}: Add {G}{G}. You gain 2 life. Whenever a nontoken creature enters the battlefield under your control, put a +1/+1 counter on it and draw a card.

Whenever a creature you control leaves the battlefield, if it had counters on it, put those counters on The Ozolith. At the beginning of combat on your turn, if The Ozolith has counters on it, you may move all counters from The Ozolith onto target creature.

Whenever another Merfolk enters the battlefield under your control, put a +1/+1 counter on target Merfolk you control.

Merfolk and Druid cards in your graveyard have retrace. (You may cast cards with retrace from your graveyard by discarding a land card in addition to paying their other costs.)

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.

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

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.

Creatures you control with +1/+1 counters on them can't be blocked.

{T}: Untap another target permanent.

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.

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

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.

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.

Flash When Merfolk Trickster enters the battlefield, tap target creature an opponent controls. It loses all abilities until end of turn.

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

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.

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.)

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

Changeling (This card is every creature type.) As Realmwalker enters the battlefield, choose a creature type. You may look at the top card of your library any time. You may cast creature spells of the chosen type from the top of your library.

Each other Wizard creature you control enters the battlefield with an additional +1/+1 counter on it. {2}, Remove a +1/+1 counter from a creature you control: Draw a card.

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

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

Untap all permanents you control during each other player's untap step.

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

Flash When Singer of Swift Rivers enters the battlefield, put a shield counter on another target creature you control. (If it would be dealt damage or destroyed, remove a shield counter from it instead.) You may cast Merfolk spells as though they had flash.

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.

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

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}.)

When Thassa's Oracle enters the battlefield, look at the top X cards of your library, where X is your devotion to blue. Put up to one of them on top of your library and the rest on the bottom of your library in a random order. If X is greater than or equal to the number of cards in your library, you win the game. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.)

Indestructible As long as your devotion to blue is less than five, Thassa isn't a creature. (Each {U} in the mana costs of permanents you control counts toward your devotion to blue.) At the beginning of your upkeep, scry 1. {1}{U}: Target creature you control can't be blocked this turn.

Flash When Tishana's Tidebinder enters the battlefield, counter up to one target activated or triggered ability. If an ability of an artifact, creature, or planeswalker is countered this way, that permanent loses all abilities for as long as Tishana's Tidebinder remains on the battlefield. (Mana abilities can't be targeted.)

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.) Whenever a creature you control with a +1/+1 counter on it dies, draw a card.

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

Flash Other Merfolk you control get +1/+1. Sacrifice a Merfolk: Counter target noncreature spell unless its controller pays {1}.

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.)

If an effect would create one or more tokens under your control, it creates twice that many of those tokens instead. If an effect would put one or more counters on a permanent you control, it puts twice that many of those counters on that permanent instead.

Whenever a nontoken creature enters the battlefield under your control, if it doesn't have the same name as another creature you control or a creature card in your graveyard, draw a card.

If one or more +1/+1 counters would be put on a creature you control, that many plus one +1/+1 counters are put on it instead.

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

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.

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.

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

As Reflections of Littjara enters the battlefield, choose a creature type. Whenever you cast a spell of the chosen type, copy that spell. (A copy of a permanent spell becomes a token.)

Return all attacking creatures to their owner's hand.

Exile up to three target enchantments. Cycling {2} ({2}, Discard this card: Draw a card.)

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

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.")

If you control a commander, you may cast this spell without paying its mana cost. Counter target noncreature spell.

Draw a card for each creature you control with a +1/+1 counter on it. Those creatures gain indestructible until end of turn. (Damage and effects that say "destroy" don't destroy them.)

Choose two — • Return target creature or planeswalker to its owner's hand. • Counter target artifact or enchantment spell. • Put two +1/+1 counters on target creature. • Target player shuffles up to three target cards from their graveyard into their library.

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

{T}: Add {C}. {G}{U}, {T}: You may cast spells this turn as though they had flash.

{T}: Add {G}. Channel — {1}{G}, Discard Boseiju, Who Endures: Destroy target artifact, enchantment, or nonbasic land an opponent controls. That player may search their library for a land card with a basic land type, put it onto the battlefield, then shuffle. This ability costs {1} less to activate for each legendary creature you control.

({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.

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.

({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}.)

Hexproof Lotus Field enters the battlefield tapped. When Lotus Field enters the battlefield, sacrifice two lands. {T}: Add three mana of any one color.

{T}, Pay 1 life, Sacrifice Misty Rainforest: Search your library for a Forest or Island card, put it onto the battlefield, then shuffle.

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.)

{T}, Pay 1 life, Sacrifice Prismatic Vista: Search your library for a basic land card, put it onto the battlefield, then shuffle.

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

As Secluded Courtyard 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 or activate an ability of a creature source of the chosen type.

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}.)

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.

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 and/or graveyard for a creature card with mana value X or less and put it onto the battlefield. If you search your library this way, shuffle. If X is 10 or more, creatures you control get +X/+X and gain haste until end of turn.

If it's not your turn, you may exile a green card from your hand rather than pay this spell's mana cost. Destroy up to two target artifacts and/or enchantments.

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.

Permanents you control gain hexproof and indestructible until end of turn.

Split second (As long as this spell is on the stack, players can't cast spells or activate abilities that aren't mana abilities.) Untap target creature. Until end of turn, it gains hexproof, reach, and "Whenever this creature becomes tapped, it deals damage equal to its power to up to one target creature."

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.

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: Create a Food token. (It's an artifact with "{2}, {T}, Sacrifice this artifact: You gain 3 life.") +1: Target artifact or creature loses all abilities and becomes a green Elk creature with base power and toughness 3/3. −5: Exchange control of target artifact or creature you control and target creature an opponent controls with power 3 or less.

Choose a creature type. Return all creatures that aren't of the chosen type to their owners' hands.