The legendary "Magick Mirror" was a scrying device, many were black. The CIA uses a black obsidian disc. The between world portal effect is accomplished by tilting the mirror slightly so no reflection is seen other then the sky or blank ceiling. For more "portal" experiments see: "The Wiccan Mysteries, Ancient Origins and Teachings" by Raven Grimassi (Appendix one "the elemental doorways".
One need not be religious to be Spiritual. A Wizard commands power to influence probabilities, stands between worlds with one foot on earth and the other in the heavens, is in tune with the Infinite, knows truth and is at peace with self and the Universe.