Annizith, Precognitive Master

You may look at the top card of your library
any time. You may cast it if it's an instant or
sorcery card.
Once each turn, you may cast an instant or
sorcery spell for double its mana cost. If that
spell doesn't have hurricane, it gains hurricane.
Once each turn, you may cast an instant or
sorcery spell for half its mana cost. If that spell
has hurricane, it loses hurricane.