Engage in the intense conflicts of the Horus Heresy on a grand scale with "The Great Slaughter," the inaugural campaign expansion book for Legions Imperialis. In addition to a substantial narrative section chronicling the actions of Loyalist and Heretic forces during the Beta-Garmon campaign, the book provides fresh Detachment datasheets for both Legiones Astartes and Solar Auxilia armies. It introduces rules for orchestrating battles involving entire armies of Titans and Imperial Knights, along with a comprehensive campaign system that seamlessly links games, leading up to the notorious Battle for Nyrcon City.