msem-instigator

Adorned — Coven Adherent has indestructible as long as it's equipped and/or enchanted.

Whenever Culling Claw attacks, target creature gains winnow until end of turn. (Damage dealt to it also causes its controller to lose that much life.)

Menace
Whenever CySec Blacksuit deals combat damage to a player or planeswalker, create a Function token with “Choose a nonland card exiled by this spell. For as long as that card is exiled, you may cast it and you mana of any type can be spent to cast that spell.” (It's an enchantment. As you cast an instant or sorcery spell, sacrifice any number of Functions to add their effects to that spell.)

Augmented — When Dead End Adventurer enters, if you've spent {W}{U}{B}{R}{G} to cast spells this turn, destroy target creature you don't control.

{B}, Sacrifice another creature: Deranged Apothecary gains indestructible until end of turn.

Mentor (Whenever this creature attacks, put a +1/+1 counter on target attacking creature with lesser power.)
{2}, Sacrifice a creature: Put a +1/+1 counter on Desert Marauder.

Assault {1}{B} (Whenever this attacks, if it has no +1/+1 counters on it, you may pay its assault cost to put a +1/+1 counter on it.)
Whenever a creature you control assaults, you may have target creature get -2/-2 until end of turn.

Menace
Whenever Diregraf Skulleater deals combat damage to a player, that player discards a card.
Whenever one or more cards leave your graveyard, put a +1/+1 counter on Diregraf Skulleater.

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.

{B}, Remove a time counter from a permanent you control: Target player loses 1 life.

{1}, Sacrifice another creature: Put a +1/+1 counter on Dread Cabalist and on up to one target legendary creature. Activate only as a sorcery.

Improve {1}{B} ({1}{B}: 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.)
Once each turn, when you gain life, you may have each opponent loses 1 life.

Menace
Whenever you cast a spell from anywhere other than your hand, each opponent discards a card if it's your turn. Otherwise, each opponent loses 2 life.

Menace
As long as you control exactly one other creature, that creature gets +1/+1 and has menace.

Whenever Fleshwarper or another Horror you control dies, each opponent loses 1 life and you gain 1 life. You may mill a card.

Lifelink
Pay 3 life: Flightful Fledgling gains flying until end of turn.

Menace
When Fortune Hoarder dies, each player discards a card at random.

Gloam Gullet gets +1/+1 and has menace as long as you own a land card in exile or in your graveyard.

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.)

Whenever you cast a black spell, you lose 1 life.

Whenever Gorran Hunter perseveres, target creature gets -1/-1 until end of turn. (A creature perseveres when it survives damage.)

When Graygulch Lurker dies, target opponent loses 2 life.

Haste
Whenever a player loses life, that player gains control of Graygulch Revenant.

Flying
When Greater Swooprat enters, creatures your opponents control get -1/-1 until end of turn.