Narstone is a substance that can only be found in the Demon Wastes, most often within The Labyrinth. It is believed by both the Carrion Tribes and the Ghaash'kala that Narstone is the fossilized essence of fiends, which accumulates in the stone of the Wastes over time as fiends are destroyed there. Eventually, the fiendish essence within the rock gains enough energy to form a sort of consciousness, which then rages against its trapped state in the rock.
Narstone is used by the Carrion Tribes to make weapons and armour, as they believe that the fiendish essence trapped within it can bless them, and curse their enemies.