Demon's Disciple

When Demon's Disciple enters, each player sacrifices a creature or planeswalker of their choice.

Blood Artist

Whenever Blood Artist or another creature dies, target player loses 1 life and you gain 1 life.

At the beginning of each player's upkeep, that player sacrifices a creature of their choice.

At the beginning of the end step, if three or more creatures died this turn, flip Kuon, Ogre Ascendant.

At the beginning of each upkeep, if you control no Snakes, create a 1/1 black Snake creature token with deathtouch.

Whenever one or more other creatures die, draw a card. This ability triggers only once each turn.

When Fleshbag Marauder enters, each player sacrifices a creature of their choice.

Flying
When Gravelighter enters, draw a card if a creature died this turn. Otherwise, each player sacrifices a creature of their choice.