I probably should keep in mind that this is the "divorced but not done" section, but reading this I still felt the need to say my piece.
My opinion is that relationships aren't just about your heart. I think it's actually a thinking thing. I think it's fair to ask yourself whether a person is right for you. So, let me present your XW to you as a person's profile you are reading on match.com
Divorced twice Cheated on my first husband, married my second husband 2 months after the ink on D was dry, divorced him within two years. Am into witchcraft.
Sound like a great catch. Someone else wrote, "would you divorce her if she started practicing wiccan while you were married?", and I think it's more appropriate to say (since you are, in fact, divorced), "Is this someone you would choose to date?"
My concern is that there is nothing different about your XW. Whatever drives her to have short-term relationships is still part of her make-up. I would be very leary of having a committed relationship with her again. I feel she wants you because she can't have you...when and if she gets you, who knows. Could you trust the longevity of a relationship with her? If you want to give her a chance, then start small with dating and don't let yourself get sucked into a big commitment. But if this Wiccan thing is a deal breaker, then don't bother.
You cannot be lonely if you like the person you're alone with. Dr. Wayne Dyer