Flash

Ward {2} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {2}.) {3}{U}{U}: Dreadlight Monstrosity can't be blocked this turn. Activate only if you own a card in exile.

Flash (You may cast this spell any time you could cast an instant.) Emerge {7}{U} (You may cast this spell by sacrificing a creature and paying the emerge cost reduced by that creature's mana value.) Drownyard Behemoth has hexproof as long as it entered the battlefield this turn.

{T}: Switch target creature's power and toughness until end of turn.

{2}{U}: Adapt 2. (If this creature has no +1/+1 counters on it, put two +1/+1 counters on it.)

{6}{U}: Monstrosity 4. (If this creature isn't monstrous, put four +1/+1 counters on it and it becomes monstrous.) As long as Skittering Crustacean is monstrous, it has hexproof. (It can't be the target of spells or abilities your opponents control.)

Draw three cards, then put two cards from your hand on top of your library in any order.

Draw a card for each Island you control.

Draw a card for each Island you control, then discard two cards.

Whenever Marit Lage's Slumber or another snow permanent enters the battlefield under your control, scry 1. At the beginning of your upkeep, if you control ten or more snow permanents, sacrifice Marit Lage's Slumber. If you do, create Marit Lage, a legendary 20/20 black Avatar creature token with flying and indestructible.

Scry 1. Draw a card.

Look at the top three cards of your library, then put them back in any order. You may shuffle. Draw a card.

When Purple-Crystal Crab dies, draw a card.

Bestow {5}{U} (If you cast this card for its bestow cost, it's an Aura spell with enchant creature. It becomes a creature again if it's not attached to a creature.) Whenever Thassa's Emissary or enchanted creature deals combat damage to a player, draw a card. Enchanted creature gets +3/+3.

Flash Enchant creature Enchanted creature loses all abilities and is a black Skeleton creature with base power and toughness 1/1. (It loses all other card types and creature types.)

Enchant creature Enchanted creature can't be blocked. Whenever enchanted creature attacks, scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Target creature can't be blocked this turn. Flashback {U} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

{T}, Discard a card: Up to one target creature can't be blocked this turn. Whenever Key to the City becomes untapped, you may pay {2}. If you do, draw a card.

Enchant creature As long as enchanted creature is attacking alone, it can't be blocked. Enchanted creature has "Whenever this creature deals combat damage to a player, it connives." (Its controller draws a card, then discards a card. If they discarded a nonland card, they put a +1/+1 counter on this creature.)

Krakens, Leviathans, Octopuses, and Serpents you control can't be blocked except by Krakens, Leviathans, Octopuses, and Serpents.

Devoid (This card has no color.) Target creature can't be blocked this turn. Draw a card.

Commander creatures you own have "Whenever this creature attacks a player, if no opponent has more life than that player, this creature can't be blocked this turn."

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.

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}.) Mystic Sanctuary enters the battlefield tapped unless you control three or more other Islands. When Mystic Sanctuary enters the battlefield untapped, you may put target instant or sorcery card from your graveyard on top of your library.

{T}: Add {C}. {4}, {T}: Target creature can't be blocked this turn.

Landfall — Whenever a land enters the battlefield under your control, target player mills three cards.

Whenever another snow permanent enters the battlefield under your control, you may have target player mill two cards.

Enchant creature {2}{U}: Untap enchanted creature. Totem armor (If enchanted creature would be destroyed, instead remove all damage from it and destroy this Aura.)

Creatures can't attack you unless their controller pays {2} for each creature they control that's attacking you.

Kicker {1} (You may pay an additional {1} as you cast this spell.) Target creature you control gets +0/+3 until end of turn. If this spell was kicked, that creature also gains hexproof until end of turn. (It can't be the target of spells or abilities your opponents control.)

Target creature you control gets +1/+1 and gains hexproof until end of turn. Untap it. (It can't be the target of spells or abilities your opponents control.)

Put a +1/+1 counter on target creature. It phases out. (Treat it and anything attached to it as though they don't exist until its controller's next turn.)

Equipped creature has hexproof and haste. (It can't be the target of spells or abilities your opponents control.) Equip {1}

Equipped creature gets +1/+1 for each land you control. Equip legendary creature {3} Equip {7}

Equipped creature has double strike. (It deals both first-strike and regular combat damage.) Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

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

{2}, {T}, Sacrifice Armillary Sphere: Search your library for up to two basic land cards, reveal them, put them into your hand, then shuffle.

{3}, Sacrifice Burnished Hart: Search your library for up to two basic land cards, put them onto the battlefield tapped, then shuffle.

Until end of turn, whenever a player taps an Island for mana, that player adds an additional {U}.

Blue creature spells you cast cost {1} less to cast. Whenever you cast a creature spell, target creature an opponent controls doesn't untap during its controller's next untap step.

Sky Diamond enters the battlefield tapped. {T}: Add {U}.

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

Equipped creature gets +2/+2 and has protection from red and from green. Whenever equipped creature deals combat damage to a player, exile the top two cards of your library. You may play those cards this turn. You may play an additional land this turn. Equip {2}

Morph {4}{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.) When Chromeshell Crab is turned face up, you may exchange control of target creature you control and target creature an opponent controls.

Counter target spell.

Return to their owners' hands all creatures with toughness less than or equal to the number of Islands you control.

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

This spell costs {1} less to cast for each snow land you control. When Icebreaker Kraken enters the battlefield, artifacts and creatures target opponent controls don't untap during that player's next untap step. Return three snow lands you control to their owner's hand: Return Icebreaker Kraken to its owner's hand.

Ward {3} (Whenever this creature becomes the target of a spell or ability an opponent controls, counter it unless that player pays {3}.) Channel — {2}{U}, Discard Mirrorshell Crab: Counter target spell or ability unless its controller pays {3}.

Counter target noncreature spell.

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

When Scourge of Fleets enters the battlefield, return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control.

Return each creature your opponents control with toughness X or less to its owner's hand, where X is the number of Islands you control. Foretell {1}{U}{U} (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.)

Create a 0/3 blue Crab creature token. Investigate. (Create a Clue token. It's an artifact with "{2}, Sacrifice this artifact: Draw a card.")

Activated abilities of creatures cost {1} less to activate. This effect can't reduce the mana in that cost to less than one mana.

Flash As Instruments of War enters the battlefield, choose a creature type. Creatures you control of the chosen type get +1/+1.

Flying Creatures you control have "Whenever this creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability."

Enchant creature Enchanted creature has flying. When Launch is put into a graveyard from the battlefield, return Launch to its owner's hand.

This spell can't be countered. You have no maximum hand size. Whenever an opponent casts a noncreature spell, draw a card. Discard three cards: Exile Nezahal, Primal Tide. Return it to the battlefield tapped under its owner's control at the beginning of the next end step.

Equipped creature gets +1/+1 and has trample and lifelink. {1}: Permanents your opponents control lose hexproof and indestructible until end of turn. Equip {2}

Whenever a Kraken, Leviathan, Octopus, or Serpent you control deals combat damage to a player, create a 9/9 blue Kraken creature token.