msem-instigator

Poisonous 2 (Whenever this creature deals combat damage to a player, that player gets two poison counters.)
Coil Remnant has deathtouch as long as an opponent is poisoned.

Whenever Coincutter Agent attacks, you draw a card and you lose 1 life.

Flash
Enchant creature
Enchanted creature gets -2/-2 and can't block creatures you control.

Haste
Coldhearted Explorer can't block.

{T}: Add {C}.
{T}, Pay 1 life: Add {B}.
{5}{B}, {T}, Sacrifice Collapsing Ridges: Return target creature card from a graveyard to the battlefield under your control. Activate only as a sorcery.

Once each turn, when you foretell a card or cast a foretold spell, you may create a tapped Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Whenever a token creature you control dies, each opponent loses 2 life.

Bleed {2}{B} (You may cast this spell for its bleed cost if an opponent has lost life this turn.)
Destroy target creature. Its controller loses 2 life.

As an additional cost to cast this spell, sacrifice a permanent in your portfolio. (Advisors, artifacts, and enchantments you control are in your portfolio.)
Draw two cards and you lose 2 life.

Mark (Whenever this creature attacks, mark target creature until end of turn.)
Whenever a marked creature dies, you lose 1 life and you draw a card.

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

Spells you cast from exile cost {1} less to cast.

Target creature gets -1/-1 until end of turn. Audition for black. (Create a 1/1 Construct Actor creature token, a Cleric Role giving 2/2 and lifelink, or a Warlock Role giving 2/1 and flying. Roles replace older ones.)

Destroy target creature. (Cast a copy of this spell once while this creature is on the battlefield.)

When Conjured Shade dies, target creature you don't control gets -1/-1 until end of turn.

Exile up to one target creature.
Coalesce {5}{B}{B} (You may cast this from your graveyard for {5}{B}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Whenever Consign to Oblivion deals damage to a permanent, exile that permanent.

Golden age (If you cast an instant or sorcery spell, activated a nonmana ability, and attacked this turn, enter a renaissance for this game.)
Destroy target creature. If you're in a renaissance, you may return a creature card from your graveyard to your hand.

Menace
Lifelink (Damage dealt by this creature also causes you to gain that much life.)

Vanishing 1 (This permanent enters with a time counter on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)
When the last time counter is removed from Conspiracy of Ravens, target player reveals their hand. You choose a nonland card from it. That player discards that card.

Look at the top card of your library. You may put it into your graveyard. Repeat this process twice, then draw a card.

Consume Creation deals 2 damage to any target and you gain 2 life.

Whenever Consuming Doom or another enchantment you control enters, you may have target creature get -1/-1 until end of turn.
Whenever a source an opponent controls destroys an enchantment you control, that player sacrifices a creature.

When Consumption Catalyst enters, create a Vial token. (It's an artifact with “{1}, Sacrifice this and another permanent: Draw a card. Activate only during your turn.”)
Whenever you draw a card, each opponent loses 1 life and you gain 1 life.

Deathtouch
Whenever a creature you control with deathtouch deals damage to an opponent, that player creates a black enchantment token named Blight with “At the beginning of your upkeep, you lose 1 life.”

When Contagious Host dies, each player loses 1 life.
Revive {2}{B} ({2}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)