Bane Stone

Not even the most learned of scholars knows the origin of the Bane Stones. Some folk maintain that the Beastmen raised them in tribute to their blasphemous gods, others that they are jagged shards of magic made manifest through careless sorcery. Whatever the truth, to battle in a Bane Stone's shadow is to invite swift death, for the stones are hungry and fresh souls are their food.

Source
pg. 124
 * Warhammer Fantasy Battle (8th Edition)