msem-instigator

At the beginning of combat on your turn, put a +1/+1 counter on Crosswind Cutter if it's a creature.
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

Hexproof
Crossworld Wanderer gets +1/+1 for each differently named land you control.

Extort (Whenever you cast a spell, you may pay {W/B}. If you do, each opponent loses 1 life and you gain that much life.)
Whenever Crowd Favorite extorts a spell, put a +1/+1 counter on Crowd Favorite.

{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.

Enchant creature
When Crown of Spores enters, germinate. (Put a +1/+1 counter on a creature or create a 1/1 green Saproling creature token.)
Enchanted creature gets +2/+2.

Equipped creature gets +2/+2.
Whenever equipped creature attacks, each opponent who controls more artifacts than you sacrifices an artifact. Opponents sacrifice creatures, enchantments, lands, and planeswalkers the same way.
Equip {1}{W}

Distorted (This creature can be blocked by tapped creatures but not untapped creatures.)
Other creatures you control with distorted get +2/+2.

Enchant creature
When Crowning Ceremony enters, draw a card.
Enchanted creature gets +1/+0.

You may play lands from your graveyard.

You may pay {B} and 4 life rather than pay this spell's mana cost.
Target creature gets -5/-5 until end of turn.

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

At the beginning of your upkeep, mill a card.
{B}, Sacrifice Cruel Consultation: Exile any number of cards from your graveyard. Create an X/X black Djinn Horror creature token, where X is the number of card types among cards exiled this way.

Target player sacrifices a creature unless they discard a creature card.
Agonize (You may cast this card from your graveyard by putting a -1/-1 counter on a creature you control in addition to paying its other costs. Then exile this card.)

Reach
Scarecrow spells you cast cost {1} less to cast.

Flying
Cruel Fledgling enters with a +1/+1 counter on it if six or more cards are in your graveyard.

Gain control of target creature until end of turn. Untap it. Until end of turn, it gains haste and “This creature can't be blocked.”
{1}, Discard Cruel Heartbeat: Add one mana of any color. Scry 1.

Destroy target creature.
Create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)

Whenever Cruising Schooner attacks, it gets +1/+1 until end of turn.
Crew 1 (Tap any number of creatures you control with total power 1 or greater: This Vehicle becomes an artifact creature until end of turn.)

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 Shrine enters tapped. When it does, it 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 this, then you may put that card into your graveyard.)
{T}: Add {G}.
{2}{G}{G}: Crumbling Shrine becomes a Nymph creature. (This effect lasts indefinitely.)

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

Creatures you control get +4/+4 and gain trample until end of turn.
Coalesce {8}{G}{G} (You may cast this from your graveyard for {8}{G}{G}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Trample

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.)