msem-instigator

Whenever you cast a black spell, choose up to X, where X is the number of black mana symbols in that spell's mana cost —
• Target player loses 1 life and you gain 1 life.
• Put a -1/-1 counter on target creature.
• You draw a card and you lose 3 life.
• Exile target card in a graveyard.

Pressure—Reappropriate black. (You may cast this spell by exiling two black cards from your hand and/or graveyard if there are seven or more cards in your graveyard.)
Destroy target creature or planeswalker.

Trample
Orodu, the Onyx Wave can't block.
Whenever Orodu attacks, defending player may sacrifice a creature. If they do, prevent all combat damage Orodu would deal this turn.

Pressure {3}{B} (You may cast this spell for its pressure cost if seven or more cards are in your graveyard.)
When Oryxyth's Brood enters, you draw two cards and you lose 2 life.

Lifelink
At the beginning of your upkeep, Osgaerith Desecrator deals 1 damage to up to one target creature.

Deception {B} ({B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
When Oshiruko Operative enters, target player loses 1 life.

When Osseous Augur enters, target creature an opponent controls gets -1/-1 until end of turn. If that creature's controller is cursed, that creature gets -3/-3 until end of turn instead.

({T}: Add {B}.)
Wanderlust — Otherworldly Swamp enters tapped unless you control four or more other differently named lands.
{1}, {T}: Add one mana of any color.

Enchant player
At the beginning of your upkeep, enchanted player loses 1 life.

When Outside the Airlock enters, create a tapped 3/2 green Horror creature token.
Whenever a creature you control dies, each opponent loses 1 life and you gain 1 life.

Target player reveals their hand. You choose a nonland card from it. That player discards that card unless they discard three other cards.

Each player discards two cards. Then if there are four or more card types among cards in your graveyard, create two 1/1 white Human creature tokens.

Target opponent reveals their hand. You may choose a noncreature, nonland card from it. If you do, that player discards that card. Otherwise, they lose 3 life.

When P-3 Ambusher enters, you may sacrifice a creature or discard a creature card. If you do, draw a card.

Lifelink
When Pact Equivocator enters, you lose 2 life and draw a card.

Enchant creature
Enchanted creature gets +1/+1 and has flying and indestructible.
At the beginning of your upkeep, sacrifice a creature.

Enchant creature
When Paid in Blood enters, create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)
Enchanted creature gets +1/+1 and has lifelink.

{T}: Target player loses 1 life.
Whenever you cast a spell from your graveyard, untap Paincaller.

Search target player's library for a card and exile it, then that player shuffles.
Coalesce {5}{B} (You may cast this from your graveyard for {5}{B}. If you do, it enters as a Horror creature after it resolves. Exile it if it would leave the battlefield or not resolve.)

Choose target player, then choose two —
• That player loses 2 life.
• That player draws two cards.
• Put two -1/-1 counters on target creature that player controls.

You draw two cards, lose 2 life, then mill two cards.

{1}, Discard a card: Painted Watcher gets +1/+1 and becomes the color of your choice until end of turn.

Whenever a creature dies, Pakka, the Shadowcloak deals 1 damage to each opponent.

Sacrifice a creature: Pale Horse gets +2/+2 until end of turn.
Ride {B} ({B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

When Paleolizard enters, you may discard a card. When you do, return target card from your graveyard to your hand that shares a type with that card.