The Ethereal Plane is one of the two overlapping Planes of Existence. These planes lay over the top of Lendahnna. A space where things exist and interact with the Material Plane. However, it is not a plane that someone can fully travel to. The Ethereal Plane is home to spirits who have not been claimed by the Gods or passed on fully. These lingering souls are gathered for necromancy. It is also possible for certain magic to allow Mortals to briefly enter into The Ethereal Plane. Most importantly a lot of the lingering spirits are not Mortals, or creatures of understanding. They are lingering denizens from the deaths during The War. Viewing The Ethereal Plane for too long can lead to mental fracturing.
Politics and Power
Gods
Nerull controls The Ethereal Plane. Commanding the spirits of the dead and hording certain dead for necromancy or other means. Locking denizens to eternal wandering in the plane after their passing.
Geography
While there is no physical geography of the plane to traverse. The Ethereal Plane does have a distinct look to those who can peer or step into it for a time. It is a light purple space where the spirits are translucent. Most of the plane is so filled with spirits that anyone who looked in would be inside of the spirits of any creature about. Most who have experienced viewing the plane suffer nausea and trauma from doing so, especially for long periods.
Denizens
The only denizens of The Ethereal Plane are the spirits and undead that exist in it’s plane. Some of the more vengeful spirits may at times rip themselves too and from The Ethereal Plane. But most must be called and bound via necromancy.