msem-instigator

Flash
Flying
{2}{B}, Exile three cards from your graveyard: Create a tapped 2/2 black Zombie creature token.

Sacrifice two other creatures: Monstrosity 2. (If this creature isn't monstrous, put two +1/+1 counters on it and it becomes monstrous.)
When Flailing Terror becomes monstrous, target opponent sacrifices two creatures.

Flying (This creature can't be blocked except by creatures with flying or reach.)
At the beginning of your upkeep, put a +1/+1 counter on Fleshrender Demon and you lose 1 life.

At the beginning of your upkeep, mill two cards.
{1}{B}{B}: Until end of turn, Gaunt Abnormality becomes a copy of target creature card in your graveyard, except it's 3/3.

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 Graygulch Turncoat enters, you may post a bounty on target creature. If you do, each opponent loses life equal to the number of bounty counters on creatures. (Put a bounty counter on that creature. It has “When this creature dies, each opponent draws a card” as long as it has a bounty counter on it.)

{2}{B}, Sacrifice a creature: Manifest the bottom card of your library. (To manifest a card, put it onto the battlefield face down as a 2/2 creature. Turn it face up any time for its mana cost if it's a creature card.)
Whenever a creature you control is turned face up, it gains deathtouch until end of turn.

When Hand of Consequence enters, creatures your opponents control get -1/-1 until end of turn.
At the beginning of your upkeep, if your fealty to Swamps is five or greater, transform Hand of Consequence. (Each Swamp you control counts towards your fealty to Swamps.)

If a player would gain life, that player adds that much {C} instead.

As an additional cost to cast this spell, sacrifice a permanent.
When Harriet, Liberated Wildborn enters, you may remove all counters from target permanent.

Sacrifice a creature: Harrowing Knight gets +2/+2 until end of turn.

Deathtouch
Discard a card: Headless Carriage gains indestructible until end of turn. Tap it.
Ride {2}{B}{B} ({2}{B}{B}: Transform this and attach it to target creature you control without a Steed. Ride only as a sorcery.)

Deathtouch
Whenever a storied permanent you control enters, remove up to two counters from target creature or planeswalker an opponent controls. (Enchantments and legendary permanents are storied.)

Assault {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.)
When Hilaback Outriders assaults, it gains menace until end of turn.

Flying
Whenever a creature you control dies, each opponent loses life equal to its power.

Whenever one or more other creatures you control die, put a +1/+1 counter on Keeper of Tradition.

Flying, lifelink
Your opponents can't search libraries.
{B}, Pay 2 life, Discard a card: Search your library for a card, then shuffle and put that card on top.

Menace
Foresight — Whenever you draw your second card each turn, search your library for a card, put it into your hand, then shuffle.

Menace (This creature can't be blocked except by two or more creatures.)
Whenever Mausoleum Revenant deals damage to a player, create a 2/2 black Zombie creature token.

Lifelink, menace

Melodae, the Favored can't be blocked by black creatures.
If Melodae would be destroyed, instead sacrifice a creature and Melodae gains indestructible until end of turn.

Deathtouch
Other creatures you control get -1/-1.
Whenever Mother Night attacks, put target creature card from a graveyard onto the battlefield under your control.

{1}{G}: Night's Guard gets +2/+2 until end of turn. Activate only once each turn.

Flying

Voracious 2 (As this enters, you may sacrifice up to two artifacts and/or creatures. This creature enters with that many +1/+1 counters on it.)
When Opportunistic Beast enters, destroy up to one target creature that was dealt damage this turn.