msem-instigator

Fleshcrawler gets +1/+0 for each player that has lost life this turn.

At the beginning of your upkeep, mill a card.
Whenever you cast a spell from your graveyard, create a 2/2 green Wolf creature token.

Enchant creature
When Grip of Paranoia enters, enchanted creature's controller loses 2 life.
Enchanted creature gets -3/-1 and can't block.

Guardian of Dusk gets +X/+X, where X is the amount of life you've lost this turn.
When Guardian of Dusk has power 13 or greater, sacrifice it. If you do, you gain life equal to its power.

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

Target creature gets -3/-3 until end of turn.
Target creature gets -3/-3 until end of turn.

Puzzlebox (Begin the game with this and another card you own from outside the game in the command zone, locked. That card is face down until you unlock this.)
{3}: Unlock Mortal's Conundrum. If the revealed card is black, put it into your hand. Otherwise, put it on top of your library.
At the beginning of your upkeep, if Mortal's Conundrum is unlocked, you lose 2 life.

Play with the top card of your library revealed.
Whenever you draw a card, destroy each creature with the same mana value as that card.

{T}: Target player loses 1 life.
Whenever you cast a spell from your graveyard, untap Paincaller.

At the beginning of your upkeep, you lose 1 life, then investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Whenever you sacrifice a permanent, each opponent loses 1 life.

Deathtouch
{U/B}: Change a target of target spell or ability that targets Serafina to another creature you control.
Whenever Serafina deals damage to a player, at the beginning of the next end step, that player loses life equal to the life they lost this turn.

As an additional cost to cast this spell, discard a card or pay {4}.
Destroy target creature.

Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)
Flashback—{B}, Pay 2 life. (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Target creature gets -1/-1 until end of turn.
Flashback {1}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

Target creature gets -6/-6 until end of turn.
Create a black enchantment token named Blight with “At the beginning of your upkeep, you lose 1 life.”

When Writhing Gateway enters, you may discard a card. If you do, create a 5/3 black Horror creature token.
{1}{B}{B}, Discard a card: Create a 5/3 black Horror creature token.

{2}{B}, Sacrifice a Clue: Target creature gets -3/-3 until end of turn.

Choose two —
• Shuffle up to two target cards from graveyards into their owners' libraries.
• Create a 1/1 black Skeleton creature token. You lose 1 life.
• Sacrifice a permanent. Draw a card.

Target opponent chooses a number. When they do, choose one —
• That player discards their hand, then draws cards equal to the chosen number.
• Archivist's Torment deals damage to that player equal to the chosen number.

Whenever Ashen Host becomes the target of a spell, Ashen Host deals 2 damage to any target.

At the beginning of each end step, if an opponent lost life this turn, you may put a +1/+1 counter on target creature.
Sacrifice a creature, Sacrifice Blood Cult Covenant: Blood Cult Covenant deals damage equal to the sacrificed creature's power to any target.

Bloodcrazed Acolyte enters with a +1/+1 counter on it for each player who lost life this turn.

Creatures you control that have been dealt damage this turn get +2/+0.
When Bloodspawn enters, it deals 1 damage to target creature you control.

Haste
At the beginning of your end step, sacrifice Breach Runner unless you return another creature you control to its owner's hand.

Whenever one or more cards are put into an opponent's graveyard from their hand or library, Cackling Tormentor deals 2 damage to any target.