Hammer of the Witches

The Imperial cannon known as the Hammer of the Witches was one of the few recovered from Fort Oberstyre before it was abandoned to its ghosts. The Great Cannon earned its name during the Gorstanford Fire of 2502, that infamous year when a young Alberich von Korden hunted down and tried a notorious witch known only as the Grey Hag. Tied to a stake in the town square, the witch was sentenced to be burned alive. The fires beneath her were lit by von Korden's own torch, but to the horror of the throng that had assembled to watch the execution, the cursed woman did not burn. Instead, she crackled louder and louder, the crackling fires beneath her echoing her laughter. As the shrieks reached a crescendo, the flames leaped out like living things, igniting the dry thatch of the buildings around the periphery of the square. Within minutes, Gorstanford burned, it's people fleeing in panic. The Grey Hag remained untouched, laughing hysterically in the center of the inferno. The disaster was only contained when an Imperial Great Cannon, under repair in the town's smithy, was hastily primed, stuffed with the nearest pile of metal (a bucket of horseshoes), and fired. The blacksmith, Bennec Sootson, claims that Sigmar was with him that day, for the cannon held true and the improvised grapeshot blasted the witch apart in a violent explosion of gore. Though the cannon was later seconded to Talabecland's grand army, during the Beast Hunt of 2520, the blacksmith Sootson still forms part of the cannon's crew, and he has claimed the wretched lives of many a witch and warlock since his conscription into the ranks.

Source

 * : Sigmar's Blood
 * : pg. 12