msem-instigator

All creatures get -3/-2 until end of turn.
Coalesce {6}{B}{B} (You may cast this from your graveyard for {6}{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.)

Haste (This creature can attack and {T} as soon as it comes under your control.)
Whenever a creature you control attacks, each opponent loses 1 life.

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.

Lifelink (Damage dealt by this creature also causes you to gain that much life.)
Cycling {B} ({B}, Discard this card: Draw a card.)

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.

Menace
Vanguard — Whenever a creature you control attacks alone, it gets +1/+1 until end of turn for each creature card in your graveyard.

Flying, trample
At the beginning of your upkeep, sacrifice a creature.
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.)

Flying
Kai'Wej, the Desolate has indestructible as long as you control no other creatures.
{1}{B}{B}, Sacrifice two creatures: Return Kai'Wej from your graveyard to the battlefield tapped.

Flying, lifelink
Other Demons you control have flying and lifelink.
If you would create a creature token, you may instead pay 5 life and create a 5/5 black Demon creature token.

Flying, trample
When Lord of Sacrilege enters, each opponent loses 3 life, discards a card, then sacrifices a nonland permanent. If you control three or more Demons and/or Warlocks, instead each opponent loses 6 life, discards two cards, then sacrifices two nonland permanents.

This spell costs {1} less to cast if you control a Warrior.

Play with the top card of your library revealed.
Whenever you draw a card, destroy each creature with the same mana value as that card.

Menace
Sabotage — Whenever an opponent or permanent an opponent controls becomes the target of a spell you control, each opponent discards a card.

Deathtouch
When Scion of Desolation enters, put target creature card with mana value 3 or less from a graveyard onto the battlefield under your control.
Whenever a Swamp you control enters, you may aetherize Scion of Desolation. (To aetherize, create a token that's a copy of it, then exile that token.)

Enspirit (As you cast this spell, you may exile a nonenchantment creature you control until this leaves the battlefield or fails to resolve. Reduce this spell's cost by the exiled card's mana value.)
Menace

First mate — Each nonland card in your starting deck is an artifact, a Pirate, or has “artifact,” “Treasure,” or “Pirate” in its printed rules text. (If this card outside the game is your chosen first mate, you may swap it with a card in your opening hand.)
Whenever Tinbeard of the Brine attacks, each opponent loses X life and you gain X life, where X is the number of artifacts you control plus the number of Pirates you control.

Menace
Titan of Fallen Stars gets +1/+1 from -1/-1 counters instead of -1/-1.
When Titan of Fallen Stars enters, move any number of -1/-1 counters from creatures you control onto Titan of Fallen Stars.

Flying
{2}{B}, Sacrifice another creature: Target creature gets -3/-3 until end of turn.

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

When Ageless Ascetic enters, return up to one target instant or sorcery card from your graveyard to your hand.

Flying, trample
Once each turn, when you cast a spell from anywhere other than your hand, you may copy it. If you do, you may choose new targets for the copy.

Flying
When Calamity Dragon enters, it deals 2 damage to each creature you don't control. Whenever a creature dealt damage this way dies this turn, Calamity Dragon deals 2 damage to that creature's controller.

Damage dealt by Deepwater Stinger can't be prevented.

Trample
When Depthlight Frontliner enters, you may salvage up to one instant card and up to one sorcery card. (Exile those cards from your graveyard until this creature leaves the battlefield. Whenever this creature deals combat damage to a player, put a card it salvaged into your hand.)

Haste
Menace (This creature can't be blocked except by two or more creatures.)
{4}{R}{R}: Ferocious Desert-Hunter gets +X/+0 until end of turn, where X is its power.