Vashtorr the Arkifane, daemon demigod of the soul forges, has fixed his gaze upon the Rock. Somewhere deep within the spacefaring battle station and fortress-monastery of the Dark Angels lies a prize that the Arkifane will spend countless lives to seize. Gathering a terrifying Balefleet around him, riding to battle aboard the most vast and grotesque Ark of Omen yet, Vashtorr closes his ironclad talons around the heart of the Dark Angels Chapter and prepares to crush it. Yet the Dark Angels are a stubborn and strategically brilliant Chapter. Even in the face of such sudden and calamitous adversity, their grim resolve comes to the fore. Rousing every warrior and weapon at their disposal, the Dark Angels dig in and prepare to fight for every corridor, every echoing chamber, dark oubliette and shadowed stairway. They are led in their defence by Supreme Grand Master Azrael, who will see the servants of the Dark Gods driven from the Rock no matter the cost. As battle rages and the fight grows ever more desperate, neither invaders nor defenders suspect that a third power moves in the shadows, preparing to strike... In this 96-page hardback book, you'll find: – The ongoing narrative of Warhammer 40,000, focusing on the ambitions of a new and powerful Chaos Daemon – Stunning photography of individual models and stirring scenes of battle, illustrating the forces fighting over the Rock – Additional rules for using six factions in Boarding Actions – Adeptus Mechanicus, Death Guard, Chaos Daemons, Genestealer Cults, Tyranids, and Necrons – Terrain component rules for Boarding Actions, detailing the effects of searchlights and camera networks, sentry turrets, and breaching robots – Eight new Boarding Actions missions, plus a system for linking your games together into a Rock Besieged campaign – Datasheets for Vashtorr the Arkifane, master of the Soul Forges, and Grand Master Azrael, reborn leader of the Dark Angels With this book, you will also receive a code to unlock Arks of Omen: Vashtorr content in Warhammer 40,000: The App.