Kakru, Soulfire Nexus

{x}{3}{u}{b}, Sacrifice a non-land permanent:
You may return target permanent from your
graveyard to the battlefield, except it is a 4/5
black and blue Demon Avatar and has haste,
flying, and indestructible. After X turns,
exile target permanent and it
cannot be regenerated.
{x}: Add X Soulfire counters to target
permanent.