Acidic Lich

Unique Skill—Whenever a nontoken creature you control dies, create a token that is a copy of
Acidic Lich. (A player can only trigger one unique
skill of a nontoken creature with the same name.)
Acidic Lich gets +1/+0 for each attacking
creature named Acidic Lich you control until
end of turn.

Don't waste your time killing something that's
already dead.