msem-instigator

Distribute four -1/-1 counters among any number of target attacking or blocking creatures.

Crossfire deals 1 damage to each creature.
Quickdraw {2}{R} (When a creature you control blocks or becomes blocked, you may cast this spell for {2}{R}.)

Search your library for up to two land cards with basic land types, put them onto the battlefield, then shuffle. Sacrifice two lands at the beginning of the next end step.

Look at the top six cards of your library. For each permanent type, you may reveal a card of that type from among them and put it into your hand. Put the rest on the bottom of your library in any order.

Flash
When Crossroads Harrier enters, it deals 2 damage to target opponent or permanent an opponent controls unless that player has you draw a card.

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}.

Reveal the top five cards of your library. You may put a creature card, enchantment card, or a card with fabled from among them into your hand. Put the rest on the bottom of your library in any order.

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.)

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.

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 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}.

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.)