Twilight, Faithful Apprentice

(Transforms into Twilight, Omnipotent Archmage)
Flash.
When Twilight, Faithful Apprentice enters the battlefield, counter target spell that targets you or a permanent you control.
Whenever a spell you control counters a spell, if there are five or more instant and/or sorcery cards in your graveyard, exile Twilight, Faithful Apprentice, then return her to the battlefield transformed under her owner's control.