Karielle And The Return Of Magic

You've been dead for over two hundred years and all of a sudden the gods want you and your husband to return to your old world to destroy another evil that threatens humanity.
Oh, sure, now you'll be an immortal and your magic will be stronger than ever, BUT, you've been instructed to find a boy. O.K., not too much of a problem. BUT, this boy isn't just any boy, he's a direct descendant of the family you belonged to. Your mission? Find this boy, train him (because he has the gift of magic too), have him help destroy the people who have brought the dark arts to your once pristine city and have destroyed all you built in your former life. And then, after you've accomplished all that, reestablish your family name and its magic in the land.
Easy for the gods to say.