The Deep Ethereal

The Deep Ethereal is a planar realm and is inhabited by various spirits and ghosts.  Its default appearance is somewhat misty, but entities with strong wills can impose their will on it to form domains. Most any kind of action in this realm involves some kind of will or belief that that action will occur.

Weaker spirits can be "summoned" or "located" by strong spirits, and souls are a valuable currency in the realm.