msem-instigator

Flying, lifelink
Improve {1}{W/B} ({1}{W/B}: Put a +1/+1 counter on this creature. This costs {1} more to activate for each +1/+1 counter on it. Improve only as a sorcery.)
Once each turn, when you gain life, you may have each opponent lose 2 life.

Whenever you foretell a card or cast a foretold spell, each opponent loses 1 life and you gain 1 life.

{2}{B}, Sacrifice a creature: Draw a card. You gain 1 life.

This spell costs {1} less to cast for each enchantment you control.
Flying, lifelink, trample
Disturb {6}{B}{B}. That spell costs {1} less to cast for each enchantment you control. (You may cast this card from your graveyard transformed for its disturb cost.)

When Archivist Heretic enters, you lose 1 life, then investigate. (Create a colorless Clue artifact token with “{2}, Sacrifice this artifact: Draw a card.”)

If a creature would leave the battlefield this turn, exile it instead.
Spell mastery — If there are two or more instant and/or sorcery cards in your graveyard, target player sacrifices a creature.

When Arisen Haploc enters, return target creature card from a graveyard to its owner's hand.
Revive {5}{B}{B} ({5}{B}{B}, Exile this card from your graveyard: Create a token that's a copy of it except it has no mana cost. Revive only as a sorcery.)

Haste
Whenever Arisen Hunter attacks, target player loses 2 life and you gain 2 life.
If Arisen Hunter would die, exile it instead.

Whenever you cast a noncreature spell, each opponent loses 1 life.
{4}, Exile Arisen Psion from your graveyard: Draw a card.

Whenever Arisen Rider attacks, creatures your opponents control get -1/-1 until end of turn.
If Arisen Rider or another creature or planeswalker would die, exile it instead.

When Arisen Troops dies, you may destroy target creature that was dealt damage this turn.

Deathtouch
Whenever another creature dies, you get a glory counter. (You lose glory counters before life. A player with ten or more glory counters wins the game.)
{4}{B}, {T}: Destroy target creature and Arrogant Entrant.

When Arrogant Orator enters, create a 0/1 black Cultist creature token with “{1}{B}{B}, Sacrifice three Cultists: Create a 5/5 black Demon creature token.”

Winnow (Damage dealt to this creature also causes you to lose that much life.)
{2}{B}: Each creature blocking Arroyo's Servant gains winnow until end of turn.

Once during each of your turns, when a card is put into a graveyard from anywhere, you may cast it. You may spend mana of any color to cast that spell.
When Arroyo, Infinitely Branching is put into your graveyard from anywhere, you may cast it.

If a player would draw a card, instead that player may put a card they own exiled with Arroyo, the Bound into their hand.
{3}: Search target player's library for a card and exile it face down, then that player shuffles. They may look at that card for as long as it remains exiled.

Flying, trample
When Ashen Persecutor enters, target opponent reveals their hand. You choose a nonland card from it. That player discards that card and you gain life equal to its mana value.

Put any number of target creature cards from your graveyard on top of your library. You draw two cards and you lose 2 life.

{B}: Remove a counter from target permanent.
{3}{B}: Move a counter from target permanent onto Ashfeaster Ghouls. Ashfeaster Ghouls can't be blocked this turn.

When Asking Imp enters, an opponent may pay 2 life. If they do, return Asking Imp to its owner's hand.

When Asphodel Gravedealer dies, choose one —
• Put a +1/+1 counter on target creature you control.
• Create a Treasure token. (It's an artifact with “{T}, Sacrifice this artifact: Add one mana of any color.”)

Flash
When Assassin of Fahrib enters, choose one —
• Destroy target creature that was dealt damage this turn.
• Scry 2.

Destroy target tapped creature.

Destroy target creature. Create a tapped Treasure token.