Each player loses a third of their life, then discards a third of the cards in their hand, then sacrifices a third of the creatures they control, then sacrifices a third of the lands they control. Round up each time.

Bottomless Pit

At the beginning of each player's upkeep, that player discards a card at random.

Tergrid's Lantern

{T}: Target player loses 3 life unless they sacrifice a nonland permanent or discard a card.
{3}{B}: Untap Tergrid's Lantern.

Tergrid, God of Fright

Menace
Whenever an opponent sacrifices a nontoken permanent or discards a permanent card, you may put that card from a graveyard onto the battlefield under your control.

Tergrid, God of Fright // Tergrid's Lantern

Grave Pact

Whenever a creature you control dies, each other player sacrifices a creature.

Smallpox

Each player loses 1 life, discards a card, sacrifices a creature, then sacrifices a land.