msem-instigator

Whenever a creature you control dies, put a loyalty counter on Dias, Freed from Belief.
[0]: Create a 2/1 black Nightmare creature token with “This creature can't block.”
[–X]: Destroy target creature or planeswalker unless an opponent pays twice X life.

Casualty 1 (As you cast this spell, you may sacrifice a creature with power 1 or greater. When you do, copy this spell.)
All creatures get -2/-2 until end of turn

You may cast this spell as though it had flash if you control a Horror creature.
Destroy all non-Horror creatures.

This spell costs {2} more to cast for each target beyond the first.
Choose one or more —
• Remove all counters from target non-Gorgon creature. If it has toughness 2 or less, destroy it.
• Return target creature or planeswalker card from your graveyard to your hand. You gain 4 life.
• Exile target player's graveyard.

Indestructible
As long as your devotion to black is less than five, Erebos isn't a creature.
Other creatures you control dying causes abilities of that creature to trigger as though it entered.
{2}{B}: Each opponent loses 1 life. You gain life equal to the life lost this way.

Once each turn, when Groz, the Nightshaper enters or you attack with one or more Horrors, you may return target nonlegendary creature card from your graveyard to your hand. Then if Groz isn't a token, create a token that's a copy of that creature card.
{2}{B}{B}, Discard Groz: Create a token that's a copy of Groz, the Nightshaper, except it's 4/4 and isn't legendary. Activate only as a sorcery.

Whenever Halford enters or attacks, an opponent chooses one. When they choose one that has already been chosen, copy that ability.
• That opponent loses 2 life and you gain 2 life.
• That opponent sacrifices a permanent.
• That opponent discards a card. If they can't, draw a card.

This spell costs {1} less to cast for each creature and/or planeswalker card in your graveyard.
Return target creature or planeswalker card from your graveyard to the battlefield.

Enchant opponent
Creatures enchanted player controls get -2/-2.
Whenever enchanted player casts a noncreature spell, they lose 2 life and you gain 2 life.

Bloodprice {B}{B}{B}{B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
Lifelink, haste
Sacrifice another Demon: Jejun, Dark Hunter gains flying and indestructible until end of turn.

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.

Whenever a player discards a card, put a +1/+1 counter on Karatuy.
When a player has no cards in hand, Karatuy becomes a Demon and gains flying and lifelink. This ability triggers only once.
Demoncycling {1}{B}{B} ({1}{B}{B}, Discard this card: Search your library for a Demon card, reveal it, put it into your hand, then shuffle.)

{B}, {T}, Discard a card: Create a 1/1 black Skeleton creature token.
{B}, {T}, Sacrifice a creature: Put a +1/+1 counter on each Skeleton you control.

When Leyline Invoker enters and at the beginning of your upkeep, you may mill two cards.
{5}{B}, {T}, Sacrifice Leyline Invoker: Return target creature card from your graveyard to the battlefield. This ability costs {1} less to activate for each creature card in your graveyard.

Return target creature card with mana value 5 or less from your graveyard to the battlefield.
Metamorph {B} (You may cast this card face down as a 2/2 creature for {3}. Turn it face up and cast it at any time for its metamorph cost.)

Flash
When Mennin Pack enters, each opponent loses 1 life.
When Mennin Pack dies, each opponent discards a card.

Whenever a creature you control dies, destroy target creature you don't control.

{U/B}{U/B}: Return Nherix, the Soulcage from your graveyard to the battlefield tapped.
{6}: Return target creature card with mana value 2 or less from your graveyard to the battlefield tapped.

Transcend (Activate as a sorcery to gain the next type and a +1/+1 counter.)
When Niu Mo Wang enters, you may have all players sacrifice a nontoken creature, enchantment, or planeswalker.
{B}: Demigod — Each player discards a card.
{X}{B}: God — Return any number of target creature cards not named Niu Mo Wang, Ashen Absolution with different mana values X or less from your graveyard to the battlefield. X can't be 0.

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.

Deathtouch
When Pestilent Scavenger enters, you may mill three cards.

(Activate each submodule once as a sorcery. When this enters, activate one submodule for free.)
{B}{B}{B}: Ambitous
Search your library for a card, put it into your hand, then shuffle. You lose 3 life.
{B}{B}{B}: Ruthless
Destroy target creature or planeswalker.
{B}{B}{B}: Determined
Power Module gains “At the beginning of your upkeep, you draw a card and you lose 1 life.”

Choose two or four —
• Search your library for a Demon card, reveal it, put it into your hand, then shuffle. You lose life equal to its mana value.
• Sacrifice a creature. If you do, draw two cards.
• Each opponent loses 2 life and you gain 2 life.
• Conjure a card named Fatigue and put it on top of your library. (It's a colorless sorcery that costs {2} with “Draw a card.”)

Target player reveals their hand. You choose a nonland card from it. That player discards that card.
Conjure a card named Fatigue and put it on top of your library. (It's a colorless sorcery that costs {2} with “Draw a card.”)

{2}{B}{B}, Exile Reclusive Augur from your graveyard: Return another target creature card from your graveyard to the battlefield. Activate only during your turn.