Previously isolated from the brutal devastation of the Horus Heresy as it tore across the Imperium, Mankind’s civil war has now reached Ultramar. The Horus Heresy Book V: Tempest tells of the Word Bearers’ treacherous attack on the Ultramarines at the mustering world of Calth, and of the cataclysmic was that will soon engulf the entire system, pitching not only the Legions against each other, but also the massed ranks of the Imperial Army militia, and the towering god-machines of the Legio Titanicus. Lavishly illustrated in full colour, this leather bound 270 page book contains an extensive history of the Ultramarines, unit profiles, and an army list as well as rules for the Primarch of the XIIIth Legion, Roboute Guilliman. To represent their part in the conflict, the rules for the Word Bearers Legion have been updated and new units and characters provided for them. The new Imperialis Militia & Cults army list allows you to field the massed troops and war machines of a range of armies raised on a myriad of worlds, including planetary defence forces and twisted Warp cults, with rules to represent your army’s unique background and fighting style. Additional units for Legiones Astartes and Mechanicum armies are presented within Tempest, such as the Sokar Pattern Stormbird, the Domitar Class Battle-automata, and rules for using the gargantuan Mars Warlord Battle Titan. Bringing this wealth of source material and game rules together, the Betrayal at Calth campaign lets you refight the apocalyptic battles between the Traitors and the Loyalists, providing missions and rules so you can either fight for Calth, or bring about its utter destruction.