Ritual Vortex of Void

When this spell is cast, reveal and exile a spell in your hand with a converted mana cost equal to {x}. You can cast that exiled spell without paying its mana cost after your next turn at instant speed as long as that spell remains exiled. Take damage equal to {x}.
The Ancients summoned something unknowable. In their Hubris, they thought to conquer the void itself.