Black Mirror
This full length ebony oval of glass is surrounded by an ornate frame. While it has been called a mirror, it does not reflect. Instead, it is a legendary gateway to countless dimensions, to an infinite number of alternate Earths. A specific incantation is needed for each dimension. After speaking the incantation, the character speaking can simply pass through the mirror into the desired world. The mirror also exists on each dimension it opens into, so passage back and forth is easy, but only for those who know the right incantation.