The Shadowfell, also called the Plane of Shadow, is a darkly lighted dimension of black, gray, and white where most other color has been leached from everything. It is a place of darkness that hates the light, where the sky is a black vault with neither sun nor stars.
The Shadowfell overlaps the Material Plane in much the same way as the Feywild. Aside from the colorless landscape, it appears similar to the Material Plane. Landmarks from the Material Plane are recognizable on the Shadowfell, but they are twisted and warped- distorted reflections of what exists on the Material Plane. Where a mountain stands on the Material Plane, the corresponding feature on the Shadowfell is a jagged rock outcropping with a resemblance to a skull, a heap of rubble, or perhaps the crumbling ruin of a once-great castle. A forest on the Shadowfell is dark and twisted, its branches reaching out to snare travelers' cloaks, and its roots coiling and buckling to trip those who pass by.
Shadow dragons and undead creatures haunt this bleak plane, as do other creatures that thrive in the gloom, including cloakers and darkmantles.
Domains of Dread
In remote corners of the Shadowfell, it is easy to reach horrific demiplanes ruled over by accursed beings of terrible evil. Beings of the Shadowfell called the Dark Powers created these domains as prisons for creatures only known as “darklords,” and through cruelty or carelessness trapped innocent mortals in these domains as well.
Shadow crossings are locations where the veil between the Material Plane and the Shadowfell is so thin that creatures can walk from one plane to the other. A blot of shadow in the corner of a dusty crypt might be a shadow crossing, as might an open grave. Shadow crossings form in gloomy places where spirits or the stench of death lingers, such as battlefields, graveyards, and tombs. They manifest only in darkness, closing as soon as they feel light’s kiss.