Andy, Ravenous Child

When Andy, Ravenous Child enters the battlefield, put a -1/-1 counter on each creature you control.
{t} Put a +1/+1 counter on Andy, Ravenous Child.
{t} Remove eight +1/+1 counters from Andy, Ravenous Child, destroy all creatures your opponents control, then put a +1/+1 counter on each creature you control.