msem-instigator

Whenever a creature dies, scry 1 and each opponent loses 1 life.

Flying
When Masked Stalker enters, target player discards a card.

Whenever one or more cards are put into exile from anywhere, target opponent loses 1 life.
Whenever one or more creatures you control deal combat damage to a player, you may pay 2 life. If you do, purge. (Exile two cards that share a type from graveyards. If you do, draw a card.)

When Maven of Fear enters, mill two cards.
Maven of Fear gets +2/+1 and has menace as long as six or more cards are in your graveyard.

When Merciless Blackguard enters, each player sacrifices a creature. For each creature token sacrificed this way, you may create a Treasure token.

Flying
Mind's Contagion has haste as long as there are two or more creature cards in your graveyard.
Whenever Mind's Contagion deals combat damage to a player, until your next turn, it gains “Noncreature spells opponents cast cost an additional 2 life to cast.”

Lifelink
Mind-Pryer gets +1/+1 as long as an opponent has one or fewer cards in hand.
Whenever an opponent discards a card, Mind-Pryer cackles. (Put a menace counter on it. If it already has menace, it deals 1 damage to each opponent instead.)

Deathtouch
When Mire Triton enters, mill two cards and you gain 2 life.

Menace
At the beginning of your upkeep, if an opponent has more cards in hand than you, you draw a card and you lose 1 life.

Poisonous 1 (Whenever this creature deals combat damage to a player, that player gets a poison counter. A player with ten or more poison counters loses the game.)
At the beginning of your upkeep, if an opponent is poisoned, you draw a card, you lose 1 life, and you get a poison counter.

Deathtouch
Mirage {1}{B} (You may cast this spell as though it had flash for its mirage cost. If you do, sacrifice it at the beginning of the next cleanup step.)

Players can't gain life.
At the beginning of each player's upkeep, if that player has 10 or less life, they lose 1 life.

Respawn (When this creature dies, if it attacked this turn, return it to its owner's hand.)

{3}{U}: Draw a card.
{2}{R}: Necropolis Battlemage deals 1 damage to target player. Scry 1.

When Night Howlers enters, target opponent reveals three cards from their hand and you choose one of them. Exile that card until Night Howlers leaves the battlefield.

Sacrifice a creature: Look at the top card of target player's library. You may have that player put that card into their graveyard.

Deception {B} ({B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
Lifelink
{1}{B}: Nimunotian Shadow gets +1/+1 until end of turn.

When Njel Crocodile enters, you may have it fight target creature. (Each deals damage equal to its power to the other.)

Wither (This deals damage to creatures in the form of -1/-1 counters.)
{1}{B}: Return Noonfiend from your graveyard to your hand.

Deception {B} ({B}, Return an unblocked attacker you control to hand: Put this card onto the battlefield from your hand tapped and attacking.)
When Oshiruko Operative enters, target player loses 1 life.

Whenever a creature dies, Pakka, the Shadowcloak deals 1 damage to each opponent.

Voracious 1 (As this enters, you may sacrifice an artifact or creature. If you do, it enters with a +1/+1 counter on it.)
Haste

Deathtouch, 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.)
{4}: Target creature gains deathtouch and lifelink until end of turn. Activate only during a player's first main phase.

Whenever Portal Inhibitor attacks, exile target nonland card from defending player's graveyard. Copy it. You may cast the copy. (You still pay its costs, including color. Copies of permanents enter as tokens.)

Flying, lifelink