msem-instigator

Flying, menace, haste
When Bloodfiend Ravager enters, it deals 2 damage to any target. If a permanent dealt damage this way would die this turn, exile it instead.
Evoke {1}{R} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Blazing Exultation deals 3 damage to any target.
{2}{R}: Shuffle Blazing Exultation and up to one other instant or sorcery card from your graveyard into your library.

[+1]: Creatures you control get +1/+0 and gain haste until end of turn.
[0]: Bennett Brooks deals 2 damage to each opponent. If you have an insight counter, create two Treasure tokens.
[0]: You get an insight counter.
[–2]: Sacrifice an artifact. If you do, return target artifact card from your graveyard to the battlefield.

Once each turn, when you cast a noncreature spell, create a 1/1 colorless Human creature token. Put a prowess counter on it.

Target player mills a card. Create a 3/2 colorless Horror creature token. Put a decayed counter on it. (It can't block. When it attacks, sacrifice it at end of combat.)

Destroy target creature with mana value 2 or less. If it was a token, you gain 2 life.

Rattlecage Terror enters tapped.
{1}{B}: Return Rattlecage Terror from your graveyard to your hand. When you do, another target creature card with mana value 3 or less in your graveyard gains this activated ability until end of turn, except it costs {1} more to activate.

Marrowskitter can't block and can't be blocked.
{3}{B}{B}: Return Marrowskitter from your graveyard to the battlefield. Create a token that's a copy of it.

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.

Flash
When Gravetiller enters, exile target creature or planeswalker card from a graveyard. If it was exiled from your graveyard, return it to your hand. Otherwise, you gain 2 life.
Evoke {B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

When Goremound enters, target creature you don't control gets -3/-3 until end of turn. All other creatures you don't control with the same name as that creature get -1/-1 until end of turn.
Evoke {1}{B} (You may cast this spell for its evoke cost. If you do, it's sacrificed when it enters.)

Choose any number of target creature and/or planeswalker cards in your graveyard. Return one of them to the battlefield and put the rest on top of your library in any order.

Create a 3/2 colorless Horror creature token. All other creatures get -3/-3 until end of turn.

Choose one —
• Exile all creature tokens.
• Exile target creature or planeswalker.
• Each opponent exiles a card from their hand and loses 2 life.

When Duskling Stalker dies, if it didn't have any counters on it, return it to the battlefield with your choice of a deathtouch, lifelink, or +1/+1 counter on it.

Whenever another creature you control dies, each opponent loses 1 life and you gain 1 life. Then you may pay {B}. If you do, Disciple of Myriad Fates becomes a copy of that creature, except it has this ability.

At the beginning of your upkeep, you may sacrifice another creature. If that creature had mana value 2 or greater, create a 3/2 colorless Horror creature token. Otherwise, create a 1/1 colorless Human creature token.
Whenever you create a creature token, you may pay 2 life. If you do, put a menace counter on it.

[+1]: Each opponent loses 1 life and you gain 1 life. Mill a card. If you do, you may shuffle a card from your graveyard into your library.
[0]: Any number of target players each discard a card. If you have an insight counter, return up to one creature card from your graveyard to your hand.
[0]: You get an insight counter.
[–2]: Target creature gets -3/-3 until end of turn.

This spell costs {3} more to cast if it targets a card in an opponent's graveyard.
Choose target creature or planeswalker card in a graveyard that was put there from the battlefield this turn. Put that card onto the battlefield under your control.

Nightshaper's Domain enters tapped.
{T}: Add {B}.

{B}: Remove a counter from target permanent.
{3}{B}: Move a counter from target permanent onto Ashfeaster Ghouls. Ashfeaster Ghouls can't be blocked this turn.

You may have Warped Physiognomist enter as a copy of any creature on the battlefield with mana value 3 or less.

Once each turn, when Vedu, the Deepdrinker enters or you attack with one or more Horrors, you may tap up to two target permanents. If Vedu isn't a token, put two stun counters on each of those permanents.
{2}{U}{U}, Discard Vedu: Create a token that's a copy of Vedu, the Deepdrinker, except it's 4/4 and isn't legendary. Activate only as a sorcery.

Improve {1} ({1}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
At the beginning of combat on your turn, target creature you control with mana value 3 or less can't be blocked this turn. If Streetwise Investigator has two or more counters on it, that creature gains vigilance until end of turn.

When Stillmarsh Brinecatcher enters, return another target nonland permanent to its owner's hand.
At the beginning of your end step, if you control a permanent with mana value 5 or greater, you may sacrifice Stillmarsh Brinecatcher. If you do, draw a card and create a 3/2 colorless Horror creature token.