msem-instigator

Sacrifice a creature or discard a card: Exile the top card of target player's library. You may cast that card for as long as it remains exiled. Any player may activate this ability but only once each turn and only during their turn.
You and permanents you control have hexproof from spells that were exiled with Mr. Jackston or that share a name with a card exiled with Mr. Jackston.

At the beginning of each player's upkeep, that player discards a card. If that player has no cards in hand, instead they sacrifice a permanent. If they control no permanents, instead they lose the game.

Destroy target creature or planeswalker. Each player loses life equal to that permanent's mana value.

At the beginning of your upkeep, each player discards a card.
Whenever Waking Watcher attacks, if defending player has no cards in hand, it gets +3/+3 and gains menace until end of turn.

At the beginning of each player's end step, if they aren't horrific, Bloody Valentine deals 2 damage to that player. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Choose one. If you're horrific, you may choose both instead. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)
• Destroy target artifact.
• Catastrophic Crash deals 3 damage to target creature.

Gain control of target creature until end of turn. Untap it. It gains haste until end of turn.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

As an additional cost to cast this spell, sacrifice a creature.
Create X Treasure tokens, where X is the sacrificed creature's mana value.

Whenever a player casts a spell, put a doom counter on Foreboding Presence.
At the beginning of each player's end step, if no spells were cast this turn, sacrifice Foreboding Presence. It deals damage equal to the number of doom counters on it to that player.

Menace
At the beginning of your end step, He of All Hallow's Eve deals damage equal to its power to you unless you're horrific. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Other creatures you control get +2/+0 and have menace.
Whenever another creature you control dies, if it wasn't sacrificed, sacrifice a creature.

First strike
Whenever a creature dealt damage by Roadside Reaper this turn dies, you may discard a card. If you do, put a +1/+1 counter on Roadside Reaper and draw a card.

Discard your hand. Draw cards equal to the number of creatures that died this turn.

Trample
Whenever a player casts a noncreature spell, that player sacrifices a noncreature permanent.

Defender
Whenever a land enters the battlefield under your control, you may exile target permanent card from your graveyard.
Sacrifice a land: Put a card exiled with Corpsebark into its owner's hand.

Haste
Whenever a creature dealt combat damage by Cutthroat Carnie this turn dies, you may have Cutthroat Carnie fight target creature.

Trample
At the beginning of your upkeep, sacrifice another creature. If you do, put X +1/+1 counters on Demented Host, where X is that creature's power.

{1}{G}, {T}, Sacrifice another nontoken creature: Create two tokens that are copies of the sacrificed creature, except they're 0/1. Activate only as a sorcery.

{T}, Sacrifice another permanent: Add one mana of any color.
At the beginning of your end step, if you're horrific, put a +1/+1 counter on target creature. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Trample
Whenever a creature you don't control dies, you gain 2 life.
Whenever you gain life, put that many +1/+1 counters on target creature you control.

You may put a permanent card from your hand onto the battlefield.
Rerun (If you cast this from your hand, exile it as it resolves. Whenever a creature you control dies, you may cast this card from exile without paying its mana cost.)

Enchant creature
Enchanted creature is a Horror with base power and toughness 3/3 and loses all other creature types and abilities.
Whenever enchanted creature deals combat damage to a creature, create a token that's a copy of Plagas Infestation and attach it to the damaged creature.

As an additional cost to cast this spell, sacrifice a noncreature permanent.
Search your library for a creature card with mana value equal to 1 plus the sacrificed permanent's mana value, put it onto the battlefield, then shuffle.

Subway Shambler can't be blocked by creatures with lesser power.
At the beginning of each end step, if you're horrific, put a +1/+1 counter on Subway Shambler. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)

Zealous Rabble gets +1/+1 for each creature token you control.
At the beginning of your end step, if you're horrific, create a token that's a copy of Zealous Rabble, except it doesn't have this ability. (You're horrific as long as you've sacrificed a permanent or discarded a card this turn.)