Bag of Holding
An osyluth (bone devil) who betrayed his lord, Bazgorca, who therefore imprisoned Sareth’tuel in a dark dimension. Freed by Lord Gregor and his high priest. Sareth’tuel then slew them both and put their corpses in his former prison. Sareth’tuel then set up the Leviathan, which has been creating the azure mist in the catacombs beneath Fair Haven.