The Wheel

"I AM ALL WE." - The only known words attributable to Iae, the GODHEAD.
At the centre of the multiverse is Iae, the GODHEAD. This is both in true in both a figurative, and a literal sense. Figuratively, creation stems from Iae's Dreams. All creatures and objects are part of the Dream and could not exist without it. In a literal sense, Iae sits in the centre of creation, slumbering in the City of Iae, which forms the Hub of the Wheel.
Were it to be given a physical form, Creation, or the multiverse, could be represented as an unfathomably vast wagon wheel. At its centre is the City of Iae, also known as The Hub, a city so vast that no Mortal Sphere in creation approaches it in scale. From The Hub sprout uncounted spokes, along which the Mortal Spheres reside. The spokes are not physical objects, but spiritual links akin to lay lines that cross some Mortal Spheres. Some seers have called the spokes the “Astral Web”. At the end of the spokes is the Rim, which circumnavigates creation, and beyond which is naught but emptiness.

by MidJourney

The City of Iae.

The greatest city in creation, it is not possible to walk from one side to the other within the span of most mortal lives. At the centre is the Barbican of the Mind, the resting place of Iae. Inside, the GODHEAD slumbers, and from her dreams spring Creation. Should she awaken, the dream ceases, along with all Creation. The Spire of Dreams is the font of all magic, drawn from Iae, and flowing through all the multiverse.
Beings of all races populate the City of Iae, though if questioned none can say how they came to be there. It has been speculated that the populace is a grand illusion springing from the mind of Iae. Access to the City is granted only by express permission of Iae, though how one would beseech a sleeping God, none can, or will, say.

The Spokes and the Mortal Spheres

Radiating from the Hub are innumerable spokes, along which are tethered the Mortal Spheres. The spokes are metaphysical in nature and not physical objects; they are spiritual links emanating from Iae, running to the Rim, linking all of Creation back to the GODHEAD. Along the Spokes sit the Mortal Spheres, immense crystal shells containing a cluster of stars, approximately 15 light years across. Whilst the crystal shells are not visible and most magics may freely pass through, immensely powerful magics are required to allow a physical object to pass.
With the turning of the ages, so turns the Wheel. This creates a force which slowly forces Mortal Spheres to drift away from the City of Iae along the Spoke they are tethered to, with the oldest Spheres colliding with the Rim and being absorbed by it. Occasionally a new Sphere is birthed on a Spoke where it intersects with the City of Iae, and the GODHEAD's latest Dream springs into Creation. Those Spheres closest to the City of Iae are known as the Heavens, and are paradises where a being's every want and need is catered for. Those furthest from the Hub are known as the Hells, and are dark places of death and despair, which bend to the whims of daemons and devils. Whilst civilisation does exist in the Hells, it is fraught with bloodshed and hardship. The majority of Mortal Spheres exist somewhere between these two extremes, though all begin as Heavens, and slowly degenerate into Hells as they age, are forgotten by the GODHEAD, and inevitably fall to entropy before being absorbed by the Rim.
The spokes may be manipulated by sufficiently powerful magics to create splinters. These splinters are small splits in the spiritual link along which a small Mortal Pocket may be created. A Mortal Pocket is a private space which bends itself to the will of the being that created it, shaping itself to their whims and desires. The power required to create and maintain a Mortal Pocket is beyond all but the most powerful of mortals, and there are few known examples that has not ended in disaster for the being who created it. Such spaces do not come without cost, mortal Pockets are an aberration in Iae’s dream, and creation will attempt to correct itself. Iae will draw beings of power inexorably to the Mortal Pocket, who will attempt to destroy both the Pocket and all beings residing inside.

The Rim

Little is known of the Rim, beyond that it is the graveyard of Mortal Spheres. Over long millennia the outermost Hell of a Spoke will slowly collide with and be absorbed by the Rim. This causes untold devastation to the Mortal Sphere itself, with all but the most powerful and hardiest beings being utterly destroyed. What survives is almost invariably the stuff of nightmares, and only the most powerful beings in Creation can hope to survive on the Rim against the horrors that reside there.

The Outer Dark

Beyond the Rim is nothingness. The GODHEAD's Dream encompasses everything within the Wheel, and those beings that pass beyond the Rim and into the Outer Dark rapidly fade from her memory and become nothing. It has been argued by deranged philosopher Wizards that in this state of fading from Iae's memory, but before becoming nothing, lies power. When one is no longer part of the Dream, mayhap one may become the Dreamer? There are no known records of beings passing beyond the Rim and surviving.

Traversing the Wheel

Most beings in Creation will be born, live their lives, and die on the same celestial body. Some might travel from one celestial body to another within the same Mortal Sphere. Rare is the individual powerful enough in magics to travel along a Spoke from one Mortal Sphere to another, though most worlds will possess such individuals. However, such feats are as child’s play compared to travelling from one Spoke to another. There are two known ways that this may occur.
The first and safest way to travel from one Spoke to another, one may travel to the Hub, and entreat the GODHEAD for permission to travel through her city. This allows access to any Spoke one should desire, but there are no accounts of how such a request may be made. The only other known method is to travel to the Rim and pass through that nightmare realm to your destination. This is understood to be far easier to access, but far less safe than attempting to access the Hub.