msem-instigator

As Citadel Gates enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {B}, {R}, or {G}.

({T}: Add {W}, {U}, or {B}.)
Coastal Dominion enters tapped.

Whenever Cocky Delinquent is dealt damage, you gain that much life and Cocky Delinquent deals that much damage to up to one target creature or planeswalker you don't control.

For each permanent type, choose up to one target permanent of that type. Exile each of those permanents, then return them to the battlefield under your control. They gain haste until end of turn. At the beginning of your next end step, those permanents' owners gain control of them.

When Cognitive Fumigator enters, target opponent reveals their hand. You may choose a nonland card from it and exile that card. If you do, that player draws a card.
Recite {2}{U} (You may cast this creature from your graveyard for its recite cost. If you do, exile it when it enters or if it would leave the battlefield.)

Concord — When Coiling Spiritscale enters, return target permanent card from your graveyard to your hand. If there are four or more card types among permanents you control, you may return that card to the battlefield instead.

{T}: Add one mana of any color.
Augmented — Whenever a nontoken creature you control enters, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, put a +1/+1 counter on it.

When Compose from Dreams enters, you may cast any number of cards named Fatigue from your hand and graveyard without paying their mana costs.
Whenever you cast a spell, each opponent loses 1 life. Then you may draw a card if that spell wasn't cast from your hand. Then add {U}{B}{R} if you don't own that spell.

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.

Legacy (You may play this side of this card only from your graveyard. Exile it if it would leave the battlefield or not resolve.)
Whenever a Warrior you control becomes the target of a spell or ability an opponent controls, that player loses 1 life and discards a card, then you draw a card and gain 1 life.

When Conflux Ravager enters, destroy target nonland permanent an opponent controls.
Cycling {2} ({2}, Discard this card: Draw a card.)

Constructed Jay is all colors.
Constructed Jay gets +1/+0 and has flying as long as you control three or more Satrapies.

Escalate {B} (Pay this cost for each mode chosen beyond the first.)
Choose one or both —
• Put target permanent on top of its owner's library.
• For each library, look at the top three cards of that library, put any number of them into their owner's graveyard, then the rest back on top in any order.

You may pay {W}{U}{B}{R}{G} rather than pay this spell's mana cost.
Flying, first strike, vigilance, trample, lifelink

When Core Paradigm enters, conjure five cards named Data-Point into your hand. (It's a sorcery that costs {2} with “Draw a card.”)
Up to three times each turn, you may cast a sorcery spell without paying its mana cost.

Menace
Whenever you cast an instant or sorcery spell, create a 2/2 black Zombie creature token. This ability triggers only once each turn.

Each player reveals the bottom six cards of their library. For each player, put up to one permanent card revealed this way onto the battlefield under your control.

When Cosmic Contraption enters or leaves the battlefield, you may reveal a noncreature card you own from outside the game and put it into your hand.

You may reveal any number of creature cards you own from outside the game with the same name and put them into your hand. Exile Cosmic Lineage.

Exchange control of target creature you control and target noncreature spell an opponent controls. You may choose new targets for that spell.

When Cou Ling enters, create two 2/1 red and white Fox creature tokens.
Whenever a Fox you control deals combat damage to a player, draw a card, then you may cast an instant or sorcery card with mana value less than or equal to the damage dealt from your hand without paying its mana cost.

Reveal the top five cards of your library. For each card type, you may put a card of that type revealed this way into your hand. Put the rest into your graveyard. Then you may cast a nonland card with mana value 3 or less from your hand without paying its mana cost.

As Coveted Tower enters, you may pay 3 life. If you don't, it enters tapped.
{T}: Add {G}, {U}, or {R}.

Flying
Cragstalker Eagle gets +2/+2 as long as you've cast a creature spell and a noncreature spell this turn.
You may cast Adventure spells and spells with Adventures from your hand as though they had flash.

Crater Burst deals 3 damage to any target. Add {W}{U}{B}{R}{G}. Until end of turn, you don't lose this mana as steps and phases end.