msem-instigator

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Whenever Conchhorn Shinygrabber attacks, you may pay {1}. If you do, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
{W}{U}{B}{R}{G}: Conchhorn Shinygrabber gets +3/+3 and gains lifelink until end of turn.

{T}: Conchspear Hunter deals 1 damage to any target. Activate only if you control three or more artifacts.

Concord — When Coral Bruiser enters, if there are four or more card types among permanents you control, put target creature you don't control into its owner's library third from the top.

Whenever Coral Hunter attacks, another target creature can't be blocked this turn.

Menace
Whenever a card leaves your graveyard for the first time each turn, invigorate 1. (Choose a creature with the least power among creatures you control and put a +1/+1 counter on it.)

Slipstream (This creature can't be blocked as long as only creatures with slipstream are attacking.)
Cycling {U} ({U}, Discard this card: Draw a card.)

Vigilance, trample
Whenever you draw your second card each turn, put a +1/+1 counter on Coralblade Cohort.
Cycling {G} ({G}, Discard this card: Draw a card.)

When Coralight Champion enters, create a white Aura enchantment token named Hila's Favor attached to target creature. The token has enchant creature and “Enchanted creature has double strike as long as there's another Aura attached to it. Otherwise, it has first strike.”

{3}{W}: Tap target creature. Activate only during your turn.

Concord — When Coralight Communer enters, if there are four or more card types among permanents you control, draw a card.

Flash
When Coralight Lifebloom enters, create a green Aura enchantment token named Kelpcrown attached to target creature you control. The token has enchant creature and “Enchanted creature has hexproof.”

When Coralight Mystic enters, create a white Aura enchantment token named Whale's Spirit attached to target creature. The token has enchant creature and “Enchanted creature has lifelink.”

When Coralight Paladin enters, you may search your library for an artifact card, reveal it, then shuffle and put that card on top.
Concord — Whenever Coralight Paladin attacks, if there are four or more card types among permanents you control, Merfolk you control get +1/+1 until end of turn.

Vigilance
When Coralight Sentinel enters, create a white Aura enchantment token named Crab's Resolve attached to target creature. The token has enchant creature and “Enchanted creature gets +0/+2.”

Whenever you cast a white spell, creatures you control get +1/+0 until end of turn.
Whenever you cast a blue spell, draw a card, then discard a card.

Corsair Sellsword can't block.
Whenever you foretell a card or cast a foretold spell, you may return Corsair Sellsword from your graveyard to your hand.

Whenever Crain's Crony enters or attacks, reveal the top card of your library and put it into your hand. You lose life equal to that card's mana value.
At the beginning of each end step, if you didn't lose life this turn, you lose the game.

{1}{R}: Crashcaller Nereid gets +1/+0 and gains trample until end of turn.

Resolute — At the beginning of combat on your turn, if Crazed Swashbuckler's power is greater than its base power, it deals 1 damage to target creature defending player controls. That creature can't block this turn.

Flying
Wanderlust — When Crest Skimmer enters, if you control four or more differently named lands, draw a card.

This spell costs {1} less to cast for each Desert you control.
When Crested Crustacean enters, return target permanent to its owner's hand.

When Gillo enters, reveal the top card of your library. If it's a land card, put it onto the battlefield tapped. If it's a creature card, put it into your hand.
As long as you control five or more creatures with different names, creatures you control get +1/+1 and have trample.

Trample
Whenever Crocheted Buddy attacks, if it's enchanted or you cast a spell that targeted it this turn, create a 1/1 colorless Construct Actor creature token.

{2}{G}: Cryptozoologist voyages. (If it isn't blocking or targeted by another spell or ability, it phases out.)
Whenever Cryptozoologist phases in, you may put a creature card from your hand onto the battlefield until Cryptozoologist leaves the battlefield. (It returns to your hand if it's still on the battlefield.)

({T}: Add {U} or {R}.)
Whenever Crystal Cavern becomes tapped, you lose 1 life unless you control two or more basic lands.