msem-instigator

When Driver of Hordes enters, create a tapped 2/2 black Zombie creature token.
Unearth {3}{B} ({3}{B}: Return this card from your graveyard to the battlefield. It gains haste. Exile it at the beginning of the end step or if it would leave the battlefield. Unearth only as a sorcery.)

Flying
When Emissary of the Wicked enters, you lose 4 life.
Revive {2}{B}{B} ({2}{B}{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.)

Pressure {2}{B}{B} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
When Gloomtide Whelk enters, all other creatures get -4/-4 until end of turn.

Menace
Disgraced 1 (This enters with a -1/-1 counter. Whenever it deals combat damage to a player, remove all -1/-1 counters from it.)

Menace
Death knell — Put a +1/+1 counter on Guiltless Wraith. (As a creature you control dies, trigger one death knell of that creature or another permanent you control.)

When Helicos-Drowned Captain enters, create a black Aura Curse enchantment token named Marked for Death attached to target player. The token has enchant player and “At the beginning of enchanted player's upkeep, that player loses 1 life.”

Flying
Whenever Herald of Shadow attacks, another target creature can't be blocked this turn.
Whenever a creature you control deals combat damage to an opponent, exile the top card of that player's library. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast it.

Lifelink
Whenever Infectious Ego enters or attacks, exile the top card of target opponent's library. If it's a land card, that player gets a poison counter. You may play that card for as long as it remains exiled, and you may spend mana as though it were mana of any color to cast that spell.

Iron Warden enters with three -1/-1 counters on it.
When Iron Warden dies, you may distribute X -1/-1 counters among any number of target creatures, where X is the number of -1/-1 counters on Iron Warden.
{2}{R}: Put a -1/-1 counter on target creature.

Flying
You may cast black spells with mana value 3 or less by paying life equal to their mana values rather than paying their mana costs.
{B}, Sacrifice another creature: You gain 3 life.

Menace

This spell costs {1} less to cast for each creature type among creature cards in your graveyard.
Deathtouch
{1}{B}, Exile any number of creature cards from your graveyard with five or more different creature types among them: Search your library for a card, put it into your hand, then shuffle. Activate only as a sorcery.

Deathtouch
Vanishing 4 (This creature enters with four time counters on it. At the beginning of your upkeep, remove a time counter from it. When the last is removed, sacrifice it.)

Flying
At the beginning of your end step, put a +1/+1 counter on Lepidopteradator if you're horrific. Otherwise, sacrifice it. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Creatures you don't control get -1/-1.

Flying
Desecrate (When this creature enters, you may sacrifice an artifact or land.)
When Liege of Luxury desecrates a permanent, target player reveals their hand. You choose a card from it and exile it. You may cast that card for as long as it remains exiled, and you may spend mana as though it were mana of any type to cast that spell.

Flying
When Lizhao, Lord of the Yaogu enters, you may put target creature card from an opponent's graveyard onto the battlefield tapped and under your control.
When Lizhao dies, each opponent sacrifices a creature.
Revive {3}{B}{B} ({3}{B}{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.)

Create a 1/1 blue Illusion creature token with “This gets +1/+1 for each other Illusion you control.”
Coalesce {6}{B} (You may cast this from your graveyard for {6}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)
Misery Keeps Company is an Illusion in addition to its other types while it's a creature.

When Monstrous Hunter enters, destroy up to one target creature.
At the beginning of each end step, if a creature died this turn, you draw a card and you lose 1 life.

Deathtouch
Whenever Operative SCARY attacks or you cast a green or white spell, you may draw a card. If you do, you lose 2 life.

Flying
Rezzal, the Loamfeaster gets +1/+1 for each nonland card exiled with it.
You may play lands exiled with Rezzal.
{1}{B/G}: Exile target card from an opponent's graveyard. Activate only outside of combat.

If a creature an opponent controls would die, exile it instead.
Whenever Rocket Poacher deals combat damage to a player, put a card exiled with it onto the battlefield under your control.

{6}: Create a 1/1 black Worm creature token.

{2}, Remove a counter from another permanent you control: Ruthless Monstrosity gets +2/+2 until end of turn.