The term "Whirlwind" was used amongst the Legiones Astartes to describe a range of vehicle-mounted multiple missile launcher systems, many of which had been recovered during the Great Crusade and were undergoing front line trials with various units. The Scorpius was a pattern that had only recently entered service during the opening years of the Horus Heresy, having been created at the behest of the Space Wolves Legion to aid in the campaign against the fortified bastion-cities of the xenos Ghassulian Sub-realms. Fighting alongside Legion Predators, with which it shares many common armour and drive systems, the Scorpius had proven itself well suited to high-intensity operations and had been approved for service across the entire Legiones Astartes.