No one knows where the war beasts known as Cruorians hail from, only that they've plagued several worlds in the Calixis Sector. The name comes from Magos Biologis Harven Cruor, who first discovered the war beasts within xenos ruins in the Bloodfall System. Massive in form, Cruorian war beasts seem to revel in battle, showing no fear even when faced by the full might of the Imperial Guard. Standing on four long legs, each ending in thick claws, and fur that ranges between dark green and blood-red, a Cruorian war beast presents a frightening aspect. Short spikes protect the head, neck, and spine, although from what one can only hazard a guess. Their forefeet have opposable thumbs, and it's possible that the Cruorian are slightly more intelligent than most think -- as witnesses have reported the use of crude melee weapons by them.
Gathering in large packs, Cruorian war beasts tend to open their hunts (or a battle) with a chorus of nerve-wracking howls, eventually reaching a crescendo right before the entire pack charges. Once engaged, Cruorian war beasts are utterly merciless and take no prisoners. In fact, some go so far as to eat the slain, even before the fighting is over. Armoured vehicles are no guarantee of protection from a Cruorian war beast charge. They are burly enough to upset smaller vehicles simply by crashing into them and have been known to work together in order to tip over larger troop carriers and the like. Due to the non-technical nature of the war beasts, the question has arisen of how they've managed to appear on such widely separate worlds in the sector. Rumours abound, ranging from the almost logical (the war beasts are being used to soften up different worlds for an invasion) to the outright inconceivable (Cruorians can pass through the Warp unaided). Of growing concern are whispered accounts of Cruorian war beasts being seen in the company of elements of the Ordo Xenos. As of yet, no one has been able to prove these allegations, but there is enough circumstantial evidence to indicate that something is going on.
- Dark Heresy: Creatures Anathema (RPG), pp. 53-54