Looming Crabithan

{t}, Exile a creature you control: Put a number
of +1/+1 counters on Looming Crabithan
equal to that creature's power plus that
creature's toughness. Activate this ability only
if no creatures are exiled with Looming
Crabithan.
When Looming Crabithan leaves the battlefield,
return the exiled creature to the battlefield
under its owner's control.