Ghost

Overview
Ghosts are beings that have died and usually move onto their respective Underworld. Anyone with a relation to Greek Mythology goes to the Underworld once they die. There, they are judged and placed into one of three places depending on their deeds in life. Ghosts do not feel pain, cannot die again, and do not age. They are permanent and do not fade. Normally, Ghosts cannot harm the living, and simply observe their day to day routines.

Tethering
As shown in The Scourge Prince, if a spell is cast on a location known as a tethering, anyone who dies at that location will be bound to the land and forced to remain their rather than going to the Underworld. This can be good or bad, for instance, if someone was good then they would be restricted from moving onto a happy afterlife (Elysium). Likewise, if a bad soul is tethered, then they can escape the Fields of Punishment and cause trouble at the tethered location. In theory, a Ghost that is tethered can exist forever in that location.