Seven Kingdoms: Seowyn's Crossing
When the Primordials were fashioning Tol, they removed some material that didn’t seem to fit and let it drift. This material collected into piles that could be referred to as “light” or “dark”. The dark material coalesced into a dark reflection of Tol which is now known as the Shadowfell.
Associated with death and decay, the darkness of the Shadowfell is seen by few mortals prior to their deaths. After death, however, most mortal spirits find their way to the Shadowfell. There, they are drawn to the halls of Oldorin, the Summerling God of Death. Once there, they are generally judged. Those that have served a particular god well are generally released to that god’s realm in the Astral Sea. Those who have bargained with Devils are remanded to those infernal beings’ custody in Hell. Those who have served no particular god in life continue to do so after death. They wander the gloom of the Shadowfell. They often become easy prey for prowling Demons who sometimes haunt areas of the Shadowfell or for the Fomorians and their Cyclops minions in the Shadowdark.