Don't know outside of the show. Didn't buy the books. If she becomes Superman, don't really care honestly.
Thus, she is invulnerable? I saw one issue where her sister became a giant centaur and was hanging around a camp of slayers, I think. I could only think of how did they deal with what the horse end did. Having watching the rear end of horses while riding them, I decided that whole scenario made the show's continuation ridiculous. In fact, creating thousands of slayers made the series ridiculous.
Mystical and bullet proof then why even have the question in the OP?