As said before, the exterior of the spiral is dangerous and could potentially destroy the spiral; also, the Wizard is from Earth (mentioned by Baba Yaga) and they are from a different dimension (hinted by Merle Ambrose). Being that the Wizard is from Earth, a world that believes in scientific discoveries instead of magic, and (to my understanding) that there's not that much known about anti-matter except the fact that it's highly reactive to matter and vice versa, could it be that the Spiral exists in dark-matter?