msem-instigator

Citadel Bagworm gets +0/+1 for each card in your graveyard.
{B}, Discard a card: Switch Citadel Bagworm's power and toughness until end of turn.

When Clawing Shaman enters from your graveyard, you may exile it. If you do, return all creature cards from your graveyard to the battlefield.
{4}{B}{B}{B}, Sacrifice a creature: Return Clawing Shaman from your graveyard to the battlefield. Activate only as a sorcery.

Sacrifice a creature: Surveil 1. (Look at the top card of your library. You may put that card into your graveyard.)

Create a 2/2 black Zombie creature token.
Tether (Then if you cast this from your hand, you may exile it tethered to a creature you control. When it dies, you may cast this from exile without paying its mana cost.)

Target creature gets -4/-4 until end of turn.

Target player reveals two cards at random from their hand. You choose one of them. That player discards that card.

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.