The mysterious Cult Mechanicum of the 31st Millennium march to war armed with esoteric and arcane science, hosts of battle-automata and cybernetic soldiers guided by the cold iron logic of their Tech-Priest overseers. The Lords of Mars command the technology that shaped the Imperium and, as the Horus Heresy consumes the galaxy, wield their arsenal for both Loyalist and Traitor causes.

This book is an essential guide for anyone who wants to command Mechanicum armies in Warhammer: The Horus Heresy. It contains the rules you need to field the various deadly and esoteric machines and troops of the Taghmata Omnissiah, whether they are loyal to the Emperor or the Warmaster. It includes Detachments, Wargear, and special rules which make the Mechanicum a unique force on the tabletop.