Astral Space

Astral Space was the first of the "Eldritch Planes" to be discovered, as early as the Second World by enterprising arcanists (the ancestors of the elves) looking for an escape from the reality of their eternal servitude to the titans. Like the other Planes, it is both functionally limitless in scope and not really of the Firmament, a place that one can physically without magic. While the Infinite Abyss manifests as a limitless expanse as well, it is not empty. It is suffused with chaotic currents and the oblivion of millenia. The Astral, by contrast, is defined by this emptiness, on such a vast scale to incomprehensible to most mortal perceptions, requiring years of dedicated training to be able to navigate, or the use of certain mediums such as charinga. Most only project their consciousness to it, as even the Commonwealth has long forgotten the means by which the elves originally left Uskara on their Great Sojourn.
Astral Space is the medium between the multiverse, with each world or reality being connected to it. It is possible for a projection to visit these other worlds. Some beings, such as Asmodeus, have made such attempts before. Others, such as Ez, hail from one of these other realities. One thing that is known however is that passing whatever barrier exists between the Astral and the Firmament will change the nature of the intruder for good, as the Principles reshape them to fit the rules of this reality. One can imagine the inverse occurs as well for any astral travelers, and some have lost themselves entirely on their dream voyages, leaving only a catatonic husk in our reality.
It is in Astral Space that it is said the Anunnaki reside, if you are a believer in such things. Being that you, dear reader, are one of these Anunnaki, I leave it to you to think of what implications that has for Uskara.