conduit from the Outer Planes to alternate prime worlds that was created by a group of deities and worshippers in the Prime Material plane. Yggdrasil is the "World Ash" that links several outer planes to the Prime Material plane, in the Norse mythos. It runs from Gladsheim, home of most of the Norse mythos, to Nifflheim, the center layer of the three Glooms of Hades and the dwelling place of the goddess of the same name. Roots and branches of Yggdrasil wind through most of the Prime worlds where these deities are recognized. The tree is a solid and permanent conduit that weathers the waxing and waning of faiths in the Prime Material and the fortunes of gods in the outer planes. The traveler is confronted with a huge tree rising from the mist of the Astral and disappearing far into the distance. The traveler can then climb the tree to the appropriate outer plane, descend to the reachable lower planes, or explore the alternate Prime worlds that the conduits touch upon. At the true terminus, the tree ends in a color pool similar to that of a fixed portal. The traveler can then pass into the outer plane as if moving into an alternate Prime Material or the Astral plane. Yggdrasil and Mount Olympus are the best-known of the permanent conduits that link the outer planes with the Prime and with other nonlinear outer planes. Magical interplanar portals generally only appear in the top layer of the outer planes, although some free-standing portals that pass through the Astral, like the Yggdrasil, pierce the lower reaches of some planes. The apertures that the Yggdrasil causes in the Prime worlds are fixed and limited to those places where the Norse gods are known. See also Parallel universes in fiction Plane (esotericism) References External links Plane of existence, D&D Glossary Dungeons & Dragons locations