The Undead Assassin

Whenever a player targets, talks about, points at
or refers to The Undead Assassin, that player
sacrifices a creature.
Whenever The Undead Assassin deals combat
damage, it deals an additional Xd6 damage where
X is the number of creatures in your party. (Your
party consists of up to one each of Cleric, Rogue,
Warrior, Wizard and Adventurer)
Don't ask him about his backstory...