Yggdrasil connects to the worlds of the Old Ring and Midgard through structures called world trees, which are magical extensions of Yggdrasil. Creatures that climb or enter a world tree might be transported onto Yggdrasil. More information on Yggdrasil can be found in the Midgard Worldbook.

The World Tree Yggdrasil is a planar pathway between worlds, but it hosts permanent inhabitants, primarily humans and ratatosk. Its great city is Grenstad, city of the five branchings, a place of ratatosk. One of the five branches from the city goes to Midgard, another to the Court of the Golden Oak in the Shadow Realm, and so forth, making Grenstad a vital hub of trade and communication. The ratatosk make the most of this position between worlds. They assert that they are not beastkin but divine messengers of the gods of Valhalla, and that they have known about the Labyrinth far longer than those minotaurs who arrived so much later. When questioned why, the ratatosk reply that they kept the secret to themselves like a prized nut buried for the winter, so of course the minotaurs get the credit for the discovery.

Created by Wolfgang Baur