msem-instigator

Enchant player
If enchanted player would shuffle their library, instead that player chooses a permanent they control and a card from their hand, shuffles them into their owner's libraries, then loses 3 life.

Exile up to six land cards from your graveyard. For each card exiled this way, create a 1/1 black Spirit creature token with flying.
Flashback {1}{B}{B}{B} (You may cast this card from your graveyard for its flashback cost. Then exile it.)

When Exiled Necromancer enters the battlefield, return target permanent card with mana value 1 or less from your graveyard to the battlefield.

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 the battlefield, 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.

When King of Bones enters the battlefield, exile up to ten target creature cards in graveyards. Each opponent loses X life and you gain X life, where X is the number of cards exiled this way.

Deathtouch
Sacrifice a creature: Target player mills two cards.

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.

Target player reveals their hand. You choose a nonland card from it. That player discards that card. You lose 1 life.
Investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

Deathtouch
Putrid Lurker can't block.
Whenever you discard Putrid Lurker or another card, you may pay {B}. If you do, return Putrid Lurker from your graveyard to the battlefield.

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.

When Sadistic Indulgence enters the battlefield, create three 1/1 white Human creature tokens with “This creature can't attack or block.”
Pay 1 life: Destroy target nonland permanent you control.

When Scion of Pestilence enters the battlefield, create a black enchantment token named Blight with “At the beginning of your upkeep, you lose 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.)

Flying
Whenever you cast a spell from your graveyard, return Unliving Swarm from your graveyard to your hand.

When Unmasker of Fate's Design enters the battlefield, look at target player's hand. Choose a nonland card from it and exile that card with a puzzle counter on it. As long as that card has a puzzle counter on it, that player may pay {2} and 1 life at any time. If they do, return the exiled card to their hand.