msem-instigator

Choose target creature you control, then choose two —
• Put a +1/+1 counter on it.
• Put a lifelink counter on it.
• That creature gains indestructible until end of turn.

Put a +1/+1 counter on target creature you control. It can't be blocked by more than one creature this turn.
Whenever a creature you control attacks alone, return Come Out and Play from your graveyard to your hand.

When Commander of the Cavalry enters, you may search your library for a creature card with ride, reveal it, and put it into your hand. If you do, shuffle.
{X}, {T}: Put a creature card with ride and mana value X or less from your hand onto the battlefield transformed and attached to another target creature you control without a Steed attached to it.

Enchant creature
Enchanted creature gets +2/+2.
When enchanted creature dies, amass Soldiers 2. (Put two +1/+1 counters on an Army you control. It's also a Soldier. If you don't control one, create an 0/0 black Soldier Army creature token first.)

Look at the top five cards of your library. You may reveal a land or Nomad card from among them and put it into your hand. Put the rest on the bottom of your library in any order.
You may play an additional land this turn.

Create a 1/1 colorless Construct artifact creature token. For each other card named Competing Design in your graveyard, create a colorless Canister artifact token with “{T}, Sacrifice this artifact: Add {C}.”

If a player would draw one or more cards except for the first one they draw in each of their draw steps, they exile a card from their hand before they draw those cards.
{1}, {T}: Until end of turn, you may play target card exiled with Compromised Vault, and you may spend mana as though it was mana of any color to cast that spell.

When Compulsory Studies enters, exile target creature until Compulsory Studies leaves the battlefield. Each player draws a card.

Discard a card: Concealed Slasher gets +1/+1 until end of turn and can't be blocked this turn.

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.

Each player draws a card, then target player mills X cards, where X is the number of cards players have drawn this turn.

Whenever you cast an enchantment spell, create a 1/1 white and black Bird creature token with flying and vigilance.
Whenever three or more creatures you control deal combat damage to a player, that player sacrifices a creature. If they can't, they discard a card.

When Conduit of the Conflux enters, scry 2.
{T}: Add one mana of any color.

At the beginning of combat on your turn, you lose 1 life and rouse 1. (Put a +1/+1 counter on a permanent you control. If it isn't a creature, tap it and it becomes a 0/0 creature in addition to its other types.)

When Confident Traveler dies, create a 1/1 white Human creature token. If Confident Traveler was sacrificed, create two of those tokens instead.

When Confine to the Oasis enters, exile target nonland permanent an opponent controls until Confine to the Oasis leaves the battlefield.
Whenever an opponent casts a spell, put a searching counter on Confine to the Oasis for each of that card's colors. Then if there are ten or more searching counters on Confine to the Oasis, sacrifice it and you gain 3 life.

When Confining Priest enters, exile another target creature with power 4 or less an opponent controls until Confining Priest leaves the battlefield. (That creature returns under its owner's control.)

Draw a card, then copy target activated or triggered ability you don't control. You may choose new targets for the copy.
Exile Confirm Hypothesis.

Target creature you control gets +1/+0 until end of turn. It fights target creature you don't control.

When Conniving Brigand enters, draw a card.

Deathtouch
Cadence (Whenever you cast a spell, if its mana value is greater than this creature's power, put a +1/+1 counter on this creature.)

Creatures you control get +1/+0 until end of turn. (Then exile this card. You may play the land later from exile.)

(Add a quest counter as this enters. Sacrifice after 3.)
1, 2 — Whenever you attack with one or more creatures with power 4 or greater, add a quest counter.
3 — Until end of turn, target creature you control gains trample and “Whenever this creature deals combat damage to a player, put a +1/+1 counter on it.”
Put two +1/+1 counters on target creature you control. It fights up to one target creature you don't control.

When Conquerer's Blade enters, create a 1/1 white Soldier creature token and attach Conquerer's Blade to it.
Equipped creature gets +1/+0 and has first strike.
Equip {3}

When Conscious Taboo enters, look at target opponent's hand. You may exile a noncreature, nonland card from it. For as long as that card remains exiled, its owner may play it. A spell cast this way costs {2} more to cast.