Energy-Box-Grenades

Equip {1}, (Item unequipped is a *+1/*+1)
( * = {e} attached if attacked,
it deals its damage to the attacker.)
Pay {x}{e} counters, attach those Energy counters to
this artifact.
Add +{x}/+{x} where {x} is equal to
the number of {e} attached to this artifact.
{t}, Sacrifice Energy-Box-Grenades deal {x} damage
to any target where {x} is
the number of attached {e} counters.