msem-instigator

If you would draw one or more cards, draw that many cards plus one instead.
When Unleashed Mindboggler dies, return it to the battlefield (front face up).

This spell costs {1} less to cast for each enchantment you control.
Flying, lifelink, trample
Disturb {6}{B}{B}. That spell costs {1} less to cast for each enchantment you control. (You may cast this card from your graveyard transformed for its disturb cost.)

Flying, lifelink
When Archdemon Shilgengar enters, exile all land cards from your graveyard, exchange your graveyard and library, then shuffle your library.
You can only cast spells by paying life equal to their mana value rather than paying their mana cost.

Indestructible
You may play cards from your graveyard.
If you would draw one or more cards, mill that many cards instead.
If a card would be put into your graveyard from anywhere other than your library, exile it instead.

Inspired — Whenever Bearer of Vile Incense becomes untapped, create a 0/1 black Cultist creature token with “{1}{B}{B}, Sacrifice three Cultists: Create a 5/5 black Demon creature token.”

Flying
Sacrifice six Swamps: Return Berbarus Unsealed from your graveyard to the battlefield with an indestructible counter on it. You draw six cards and you lose 6 life.

Bloodprice {4}{B} (You may cast this card by sacrificing a creature and paying its bloodprice.)
At the beginning of your upkeep, if there are five or more creature cards in your graveyard, create a 2/2 black Demon creature token.

This spell costs {2} less to cast for each creature that died this turn.
Flying, trample

{1}{B}, Sacrifice another creature: Draw a card and create an Idol token. (It's an artifact with “{1}, Sacrifice this artifact: Put a +1/+1 counter on target creature. Activate only as a sorcery.”)
{2}{B}, Sacrifice three Idols: Return Demon of Hubris from your graveyard to the battlefield. Activate only as a sorcery.

When Doomstep Giant enters, each player sacrifices a land.

This spell costs {1} less to cast for each card put into your graveyard from anywhere this turn.
At the beginning of each player's upkeep, that player loses 1 life, discards a card, and sacrifices a creature.

Flying, lifelink
Fallen Celestial can't block or be blocked by Angels, Demons, or Faeries.
At the beginning of each opponent's upkeep, that player loses 1 life and creates a 1/1 black Faerie creature token with flying.

Menace
Whenever Flayed Dunerazer attacks or blocks, sacrifice a permanent.

Menace (This creature can't be blocked except by two or more creatures.)
Swampcycling {2} ({2}, Discard this card: Search your library for a Swamp card, reveal it, put it into your hand, then shuffle.)

Lionize {2}{B} ({2}{B}, Exile this card from your hand: Put a +1/+1 counter on target creature and it gains the following abilities until end of turn. You may cast this card on a later turn from exile.)
Flying
Sacrifice a creature: Put a +1/+1 counter on this creature and tap it. Any player may activate this ability.

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, trample
At the beginning of combat on your turn, an opponent may sacrifice a creature. If they do, you may sacrifice a creature. If you do, repeat this process. If you don't, tap Kai'Jun.

Menace
When Lord of Decay enters, put a -1/-1 counter on it and each creature you don't control.

Flying, trample
Nether Fiend enters with a lifelink counter on it.
{B}{B}, Pay 6 life, Remove a lifelink counter from Nether Fiend: Draw six cards.

Menace (This creature can't be blocked except by two or more creatures.)
Civilized — Whenever Subjugator of Empires attacks, if you control an artifact, a creature, and an enchantment, each opponent discards a card, sacrifices a creature, and loses 3 life.

As an additional cost to cast this spell, exile X cards from your graveyard.
You draw X cards and you lose X life.
Coalesce {8}{B} (You may cast this from your graveyard for {8}{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 one or more creatures you control deal combat damage to a player, that player discards a card. Then that player may discard another card. If they don't, create two 2/1 black Nightmare creature tokens with “This creature can't block.”
Fleeting {1}{B}{B} (You may cast this spell for its fleeting cost. If you do, sacrifice it at the beginning of the next end step.)

Whenever Breakneck Barque becomes blocked by a creature, Breakneck Barque deals 3 damage to that creature.
Crew 3 (Tap any number of creatures you control with total power 3 or greater: This Vehicle becomes an artifact creature until end of turn.)

Whenever Byway Bruiser enters or leaves the battlefield, you may have it deal 3 damage to any target.

Desert Wurms can't be blocked by creatures with flying.
When Desert Wurms enters, create two 6/6 red Wurm creature tokens with “This creature can't be blocked by creatures with flying.”
When Desert Wurms is put into a graveyard from anywhere, shuffle it into its owner's library.