Planes Of Existance

Material Plane and Its Echoes
Selen resides on the Prime Material Plane.

The Feywild and the Shadowfell are it's reflections.

The Shadowfell stretches far and has been poorly explored though rumour spread of a land beyond where the God of Death resides, a place where no light reaches, and those who stray too far never return.

Transitive Planes
The Ethereal Plane and the Astral Plane are mostly featureless planes that serve primarily as pathways to travel from one plane to another.

 The Ethereal Plane , the Misty Expanse, Endless Fog or simply the Eather, is a transitive misty, fog-bound dimension that is sometimes described as a great ocean bridging the divide between the Material and the Inner planes. That isn't to say this plane is empty as various elemental features have been "imported" over millenia by different beings.

Numerous cities float through the Eather, built atop monolythic sky-islands, finding them however is extremely difficult and neigh on impossible for those who are inexperianced in traversing the Eather.

 The Astral Plane  is the realm of thought and dream, where visitors travel as disembodied souls to reach the planes of the divine and demonic. It is a great, sea, the same Above and Below, with swirling wisps of white and gray streaking among motes of light resembling distant stars. Erratic Whirlpools of color flicker in midair like spinning coins. Occasional bits of solid matter can be found here, but most of the Astral Plane is an endless, open domain.

The Inner Planes
The four Elemental Planes (Air, Earth, Fire, and Water), plus the Elemental Chaos that surrounds them, are the Inner Planes.

The Outer Planes
Sixteen Outer Planes correspond to the eight non-neutral alignments and shades of philosophical difference between them.
 * Mount Hope (LG)
 * Shadowlands (LE)
 * The Endless Steppe (CN)
 * Forest of Tomes (LN)
 * Garden of Eternal Youth (NG)
 * Astral Recepticle (L)

The Positive and Negative Planes
These two planes enfold the rest of the cosmology, providing the raw forces of life and death that underlie the rest of existence in the multiverse.