Ermberm, Devouring Ancient

{1}{r}{r} Sacrifice target creature you control, Ermberm, Devouring Ancient gains +1/+1 counters equal to that creatures power. This ability may only be activated once per turn.
At the beginning of your next end step remove all +1/+1 counters from Ermberm, Devouring Ancient and deal damage equal to the amount of +1/+1 counters to any target.