Lavaback Rat

Sacrifice Lavaback Rat: Target opponent loses life equal to Lavaback Rat's toughness. Return Lavaback Rat to the battlefield tapped at the beginning of the next end step.
Lavaback Rat's toughness is equal to one quarter the number of Lavaback Rat's in play under your control. If there is only one in play, that creature's toughness is 1. (A deck may have any number of creatures named Lavaback Rat.)