Mr Eaten

At the beginning of your upkeep, put a Peckish counter on Mr. Eaten, then lose 1 life for each Peckish counter on Mr. Eaten.

During your turn, Mr. Eaten is a creature in addition to his other types.
Mr. Eaten has power and toughness equal to 20 minus your current life total. Mr. Eaten cannot be blocked if he is attacking a planeswalker.

{t}: Mr. Eaten fights target creature.