Shadowfell

The Shadowfell, also known as the plane of Shadow, was a sort of counterpart to the Feywild, in the sense that it was a reflection, or "echo", of the Material Plane. Unlike the Feywild, it was a bleak, desolate place full of decay and death.

Description

The most striking and immediate impression a visitor to the Plane of Shadow experienced was the lack of color and light; no sun, moon, or stars adorned the vault of the inky black sky, and all things looked as if the color had leeched out, leaving nothing but black and white, which in the dimness were more like "dark black" and "light black".
Upon entering the Plane of Shadow, the local features were usually quite similar: casting shadow walk in a forest put you in a shadow forest; casting it underwater dropped you in a similar body of water, etc. But from that starting point, the landscape diverged rapidly away from the familiar, and on subsequent visits from the same starting point, it diverged in different ways, making mapping the Shadowfell a useless endeavor. Landmarks were usually recognizable but altered in some bizarre way: buildings might be constructed in a different style, built with different materials, at a different location, and/or in any condition from dilapidated ruins to its normal appearance, for example, or otherwise strange and distorted.
Some areas on the Plane of Shadow seemed to have an affinity with the Negative Energy Plane and life-draining undead such as shadows, ghosts, and vampires. These "darklands" had a minor negative-dominant trait and unprotected visitors immediately felt the life force being sucked from their bodies—unless they exited the darkland quickly, all that was left of them was a pile of ash. Someone with protection from negative energy could stop and admire the utter desolation in an otherwise forlorn landscape, and perhaps make the acquaintance of the truly inimical undead.
Other less dangerous but quite unsettling echoes occurred in areas analogous to towns and cities in the Prime Material Plane. They were nothing more than mirages, but familiar faces and places as seen through the macabre mirror of the Shadowfell could be very demoralizing. Structures might appear altered, dislocated, destroyed, or replaced entirely by something else. Mirages of the living had visages of distorted nightmares but were still recognizable enough to give travelers a jolt of fear and revulsion
Air, water, and food existed on this plane, supporting plants, animals, and some humanoids adapted to the shadow environment. Visitors could survive indefinitely if they were willing to endure thick, foul-smelling water, food that oozed dark blood, and a pervasive nip of cold in the air. A visitor could never feel warm, would often hear or sense the presence of things that weren't there, and could never shake the feeling of being watched.

Cosmology

According to early versions of the Great Wheel cosmology, the Plane of Shadow was considered only a demiplane. The largest of these was called the Demiplane of Shadow and was made up of both positive and negative energy in equal measure.
After the rise of Altoron, and The Great Collapse, the negative energy projected from the material plane gave rise to a large amount of power. This power was utilized by Erebus, The Whispered One, who used the energy to shift the Shadowfell's position and size to become an "echo" of the Material Plane, and since this event, it has remained as such.

Color Pools

Spiraling black

Ethereal Curtains

Silver or dusk gray

Shape and Size

Infinite

Gravity

normal

Time

Normal

Type

Dimensional plane