msem-instigator

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.

Whenever you cast a spell, you may pay 3 life. If you do, draw a card.

Equipped creature gets +2/+1.
Whenever equipped creature becomes the target of a spell or ability for the first time each turn, counter that spell or ability.
Equip {2}

{T}: Add one mana of any color.
{3}, {T}, Sacrifice Coveted Heirloom: Draw a card.
Tap three untapped artifacts you control: Return Coveted Heirloom from your graveyard to the battlefield.

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

Cradle of Corruption enters tapped.
Whenever a creature dies, put a creation counter on Cradle of Corruption.
{T}, Remove ten creation counters from Cradle of Corruption and sacrifice it: Put up to two target creature cards from graveyards onto the battlefield under your control. Activate only as a sorcery.

Cradle of War enters tapped.
{3}, {T}: You may put an artifact card with mana value 3 or less from your hand onto the battlefield. This ability costs {1} less to activate for each other artifact you control. Activate only as a sorcery.

Crafted Coast enters tapped unless another player controls a land that could produce {W} or {U}.
{T}: Add {W} or {U}.

Equipped creature gets +2/+0 and has flying.
Equip {2} ({2}: Attach to target creature you control. Equip only as a sorcery.)

{2}, Exile Cranial Archive: Target player shuffles their graveyard into their library. Draw a card.

Flash
When Cranial Glass enters, exile target card from a graveyard.
{7}, {T}, Sacrifice Cranial Glass: Copy the exiled card. You may cast the copy without paying its mana cost. (A copy of a permanent spell becomes a token.)

{T}: Add {C}.
{3}, {T}: Scry 1. (Look at the top card of your library. You may put that card on the bottom of your library.)

Cresting Bay enters tapped unless you control a basic Island.
{T}: Add {U}.
{2}{U}{U}: Until end of turn, Cresting Bay becomes a 3/3 blue Elemental creature with “Whenever this creature attacks, you may draw a card then discard a card.” It's still a land.

You may have Crossroads Town enter tapped. If you do, search your library for a basic land card, reveal it, then shuffle and put that card on top.
{T}: Add {C}.

{T}: Add {C}.
{T}: Add one mana of any color. Spend this mana only to cast a creature spell with a creature type no creature you control has.

Equipped creature gets +X/+X, where X is the number of cards in your graveyard.
Sacrifice a creature other than equipped creature: Equipped creature gains lifelink and indestructible until end of turn.
Equip {3}

You may play lands from your graveyard.

{2}, {T}: Draw a card. Crude Tablet doesn't untap during its controller's next untap step.

Crumbling Aqueduct enters tapped unless you control another Desert.
{T}: Add {U} or {B}.

Crumbling Necropolis enters tapped.
{T}: Add {U}, {B}, or {R}.

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

Crumbling Vestige enters tapped.
When Crumbling Vestige enters, add one mana of any color.
{T}: Add {C}.

Up to one target creature you control has base power 4 until end of turn. (Then exile this card. You may play the land later from exile.)

When Crux Pinnacle enters, for each color, exile up to one target permanent of that color until Crux Pinnacle leaves the battlefield.
Whenever a player casts a spell, if there are five or more spells on the stack, you win the game.

{T}: Add {C}.
{X}: Crypt of Myriad Fates becomes a copy of target creature card with mana value X or less in your graveyard until end of turn, except it's 2/2 and a land in addition to its other types. Activate only outside of combat.