Abaddos

Abbados is a demesne near Hell claimed by a powerful and evil entity known as Mephisto.

Mephisto deals in souls and spirits and is well known as a collector of lives. He offers Faustian pacts to particularly potent individuals, and entraps them in Abaddos so their suffering grows his realm.

Mephisto's ambition is to overtake Hell from the outside, by increasing his home's harmony so that it exceeds the suffering and anger present in Hell itself. If he gains sufficient influence and power, it is entirely possible that Abaddos might slide into Hell and Mephisto would have enough power to contend with the Hellions or the Lords of Hell.