Sorrow's Furnace is a difficult explorable area under the Shiverpeak Mountains. The area contains the mining operations of the Stone Summit and is overrun with new types of Summit units. It is recommended, if entering the Furnace for the first time, to take on the quest "To Sorrow's Furnace", and its sub-quests, as they present a primer to the area. High Priest Alkar suggests that the Furnace used to be under Deldrimor control.