The Umbral Realms, also known as the "Plane of Shadow," the "Bleak Gates," or the "Shadowfell," were an echo of the Material Realm exhausted of magic and devoid of emotion. All sensations, both sensory and emotional, were lessened for any creatures on the Realm, and its landscape was a desolate place full of decay. The plane lacked light, and and all things looked as if the colour had leeched out, leaving nothing but dim black or white.
As it ran parallel to the Prime Material, its geography was similar although not entirely identical to that of the Material, but the natural landscape was markedly more stark. Upon entering the Umbreal Realms, the local features were usually quite similar, but diverged rapidly away from the familiar the further an interloper traveled, eventually and eventually broke into the Gloomshrouds. Due to the ever-changing geography, the Umbral Realms were subject to relatively frequent but very small earthquakes referred to as "shadow quakes". Similarly, time did not flow at the same rate depending on the place; lost time could suddenly "catch up" to a mortal, sending them into fits of exhaustion or hunger, or even killing them instantly if many years had passed.
They were considered the effective opposite of the Vivid Realms in the Cosmic Wheel cosmology.