Song of Sadness
Entraize Stones are floating stones that exude a bright blue glow. They can be created out of exotic, dark colored rocks. They are essentially unheard of in the material plane.
Usually, entraize stones are shaped as a diamond, cube, pyramid, or some other polyhedron. They also tend to be fairly large, about 3 feet on a side (about the size of a small refrigerator. The size and shape are picked in order to maximize their effectiveness in opening planar portals, and the runes and magic infusions are made to enhance this further.
Arvius the Witch Doctor is able to build and craft these stones. The process does not require any material particularly exotic, but it does require a vast knowledge and a time period of about ~5 days.