“There are songs there, but none I’d sing with pleasant company. Pleasures there too, but none you’ll feel good about afterwards.” - Orpheus
The Shadowfell was originally created during the closing events of the Age of Towers. It is a nightmarish mirror to Dorod. Created by the negative aspects of the human psyche, it is perpetually dark and hospitable only to the dead.
The plane is home to legions of shades and other undead. It is the original birthplace of such creatures, and before its conception, none preyed on the living. Many vampires fleeing green tide on Dorod journeyed, if they were able, to the Shadowfell. The dark crossings they used can still be found in places never touched by Ipollox.
The Shadowfell had a happy twin, the Feywild, but contact with the historical plane has not been established since the Androform Age. It was said to be created of the wild and wonderful aspects of the then-primitive humans.