A wirewolf is a monstrous Chaos machine in the service of Magister Anakwanar Sek's forces. They are powered by a trapped daemonic entity, in the same fashion as a Defiler, but can take a variety of shapes and forms, depending on their makers (ranging from knights in full armour to actual hounds).
When inactive, Wirewolves hang from specially fashioned "gibbets", where arcane practices had made the space thin so that the Immaterium could finger its way through the aether when the correct commands came. They could be summoned by wandering "glyfs" (sentient Chaos runes) at the slightest hint of disturbances from the enslaved population. Once awoken, they were known to be quite uncontrollable, often attacking friends and foes alike.
The downside to the usage of Wirewolves is that they expend their energy quickly, and must periodically return to their "gibbets" to recharge. But when they were fully awoken, there was little that could stand before their assault.
When damaged enough or destroyed, the Wirewolves' ruptured metal carcasses are torn open, unleashing the contained energy in a ferocious explosion that could potentially kill anyone within its blast radius.