The Meathook Massacre

When The Meathook Massacre enters the battlefield, each creature gets -X/-X until end of turn.
Whenever a creature you control dies, each opponent loses 1 life.
Whenever a creature an opponent controls dies, you gain 1 life.

Tattered Mummy

When Tattered Mummy dies, each opponent loses 2 life.

Serrated Scorpion

When Serrated Scorpion dies, it deals 2 damage to each opponent and you gain 2 life.

Spirit of Malevolence

When Spirit of Malevolence dies, each opponent loses 1 life and you gain 1 life.

Strangling Grasp

Enchant creature or planeswalker an opponent controls
At the beginning of your upkeep, enchanted permanent's controller sacrifices a nonland permanent, then that player loses 1 life.

Vengeful Strangler

Vengeful Strangler can't block.
When Vengeful Strangler dies, return it to the battlefield transformed under your control attached to target creature or planeswalker an opponent controls.

Vengeful Strangler // Strangling Grasp

Killing Wave

For each creature, its controller sacrifices it unless they pay X life.