Spell-Ebber Hydra

As an additional cost to cast Spell-Ebber Hydra,
exile an instant or sorcery card from your hand
with converted mana cost X.
Spell-Ebber Hydra enters the battlefield with X
+1/+1 counters on it.
Whenever Spell-Ebber Hydra attacks, you may
copy a card exiled with Spell-Ebber Hydra. If
you do, you may cast the copy without
paying its mana cost.