msem-instigator

Target player discards two cards unless they discard a noncreature, nonland card.

{B}, Sacrifice a creature: Target player loses 2 life.
{B}, Reappropriate: You gain 2 life. (To reappropriate, exile exactly two cards from your hand and/or graveyard.)

When Hand of the Murder enters, if you control a creature with a +1/+1 counter on it, create a 1/1 black Bird creature token with flying.

Whenever a permanent with one or more counters on it is put into your graveyard from the battlefield, it deals that much damage to any target and you gain that much life.

Exile target creature or planeswalker, then for each counter on that permanent, you may put a counter of that kind on a permanent you control.

{1}, Sacrifice a creature: Desperate Forsaken gets +1/+1 until end of turn. You gain 1 life.

As an additional cost to cast Deepmire Abomination, reappropriate or pay {2}. (To reappropriate, exile exactly two cards from your hand and/or graveyard.)
Menace

Deathtouch
When Deadwood Terror enters from a graveyard, create two tokens that are copies of it.
{4}{B}{B}, Sacrifice a creature: Return Deadwood Terror from your graveyard to the battlefield. Activate only as a sorcery.

Dead-Set Duo can't block.
Whenever Dead-Set Duo deals combat damage to a player, you may pay {B} and sacrifice it. If you do, they discard two cards.

Broken Deathbringer gets +1/+0 as long as you have 10 or less life.
Broken Deathbringer gets +1/+0 as long as there are one or fewer cards in your hand.

When Battery Courier dies, lose 2 life.

Reconstruct {4}{B}{B}{B} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)
Destroy all creatures. If The Afterlife Takes Its Due was reconstructed, create an X/X black Zombie Horror creature token, where X is the number of creature cards that have been put into graveyards this turn.

As an additional cost to cast Acid Sewage, reappropriate or pay {3}. (To reappropriate, exile exactly two cards from your hand and/or graveyard.)
Destroy target creature.

Flash (You may cast this spell any time you could cast an instant.)
When Wind-Blessed Guardian enters, you may return target permanent you control to its owner's hand.

Triplicate Terror can't be blocked unless defending player pays {3}. (They pay it once each combat.)

Tap target creature, then draw X cards, where X is its mana value.

Counter target spell unless its controller pays {2}.

Flying
At the beginning of your upkeep, you may pay {1}. If you do, put a +1/+1 counter on Swarm of the Dispossessed.
Sacrifice Swarm of the Dispossessed: Counter target spell with mana value X, where X is the number of +1/+1 counters on Swarm of the Dispossessed.

Supply Run costs {2} less to cast if a creature you controlled attacked this turn and wasn't blocked.
Draw two cards.

Return target creature to its owner's hand. If it's tapped, you may put it into its owner's library second from the top instead.

Rediscover an artifact card, then do the same for creature, enchantment, instant, land, planeswalker, and sorcery. (Each time, look at the top card of your library. You may reveal it and put it into your hand if it's of that type. Otherwise, put it back or into your graveyard.)

As an additional cost to cast Reality Reversal, return X nonland permanents you control to their owners' hands.
Return X plus one target nonland permanents to their owners' hands.

Tap up to two target creatures. Those creatures don't untap during their controller's next untap step.
Reconstruct {3}{U} (You may cast this from your graveyard for its reconstruct cost reduced by the mana value of a permanent you sacrifice as you cast it this way. Then exile this.)

Flash
Defender
When Imposing Barricade enters, target creature doesn't untap during its controller's untap step for as long as you control Imposing Barricade.

{U}, Sacrifice Imperious Nixie: Return target creature to its owner's hand.