The Bodhisattva Anointed by Dark Water/ The Silver Prince- Author of the tome Matthias found as well as deity of the Skullstone Archipelago as described by August.
The Calendar of Setesh- A large wrought iron orb floating above the center of the city, it twitches and rotates occasionally. Supposedly it allows a sense of the passing of time as well as serves as a prison for the servants of the Harbingers. Long ago it allowed the sun to rise and set.
The College of the Dead- The current ruling power of The Underworld, The Voice of Eset acts as Headmaster among a Council of her own choosing. It lies in the direct center of Stygia in the former palace of the Dual Monarchy.
Dual Monarchy- The “true” rulers of the Underworld, a black and white king and queen. They “appear when they are needed” but have chosen who rule in their stead. The Voice of Eset is their current chosen.
Harbingers- 13 former rulers of the Underworld, they served the elder gods slumbering deep within the Labyrinth. They have long been dead. Zozma refers to them as Deathlords.
Nephwracks-Former human spirits turned Spectres. They have existed for ages, and their constant exposure to Oblivion has causes them to leave their human forms behind, becoming twisted and deformed.
Servants of the Harbingers- Individuals formerly bound into the service of the Harbingers, they are now imprisoned in the Calendar of Setesh. You have yet to put a name to these creatures though Zozma claims they are living.
Soulsteel- A metal made from the condensed souls of the dead, it is one of the only materials able to harm ghosts.
Sigil- The plane of doors. The party is trying to reach it via the Calendar of Setesh in order to return into the world of the living.
Stygia- Central city of the dead.