Oh, right, combat tactics. The Void Stalkers (XXth Legion) are highly competent in void warfare and are often responsible for engaging the enemy in outer space (in the form of space battles and boarding actions), dropping down onto the surface of the target world once void superiority is established. They are relentless and inexorable, and a favored tactic is to abduct enemy commanders so that Gorseval may break their mind personally to obtain crucial information.