Yggdrasil
Yggdrasil, the World Tree, is a colossal tree, the base of which supports the Vashnar Mountains and the very Pillars of Heaven. It is said to stretch through not only much of Sapience, but a good majority of the planar multiverse as well. Nestled in its branches is the draconic planar nexus known as the Parthren Gare, while the lowest tips of its roots pierce the infernal plane of the Underworld. By way of Yggdrasil, the Gods and any They permit may travel with ease to any plane in existence. The best view of the tree is said to be in the Garden of the Gods itself, where one can see it stretching high into the sky in all its glory.
The most famous feature of the World Tree is the Flame of Yggdrasil.
In the year 758 AF, the mysterious Vigil guided adventurers from all over into awakening the elemental conduits of Earth, Wind, and Ocean under the pretence of wanting to protect the Prime Material Plane from the effects of the war that raged on the Elemental planes. Instead, combining the power of the conduits and that of blood sacrifice, they released Pazuzu, the demon prince from his long-time prison. Exultant with his freedom, the demon prince killed his old-time jailor, Sh'Fah and corrupted the world before at last fleeing from a legion of Kx'Khrah bent on his recapture. The demon fled to the Flame of Yggdrasil, cleaving a portal into parts unknown. This act turned the life-giving flame into a doorway, allowing adventurers to enter the planar highway of the World Tree and visit the different planes and worlds held within its branches.
The World Tree hosts several planar tiers known and unknown such as:
Flora and Fauna
A diverse array of extraplanar wildlife can be found braving life upon the illusory branches, including gobies, black-capped kingfishers, blue quails, cave crickets, spined caterpillars, killer honeybees, and a species of huge, venomous rats which are known to set upon unwary travellers. The Great Ausafoss cascades from the higher branches, coursing through the verdant Valdblomskog and about the World Tree's trunk.
References
The fabled shard of Yggdrasian flame, a rare artefact sold at auction in 541 AF, is an encapsulated fragment of the World Tree's resurrective potency which returns adventurers to life from any location. There are a number of other salubrious artefacts deriving their wholesome powers from the sacred tree including the Yggdrasian splinter and Yggdrasian vial. Finally a number of themed talisman artefacts are also available only through the Yggdrasil talisman set.