Moro Mindfire

Whenever an instant or sorcery spell you
control deals damage for the first time each
turn, exile the top card of your library. If
the exiled card has mana value less than
the damage dealt, you may cast it without
paying its mana cost.
{x}{2}{r}: The next instant or sorcery spell
you cast this turn gains "This spell deals X
damage to any target."