This 48-page softcover supplement contains:
Background and lore:The story of the Dropsite Massacre, from the first reports of the Warmasters treachery to the revelation of betrayal.
Unit Profiles:Rules for the Master of Descent, Augur Command and Control Squad, and Hyperios Missile Tank.
Additional rules:The Interdiction Cadre Prime Advantage and Battlefield Assets rules add extra dimensions to your games.
Legendary scenario:The First Wave Mission lets you recreate the initial assault of the army of the Retribution Fleet as they first set foot on the black sands of Isstvan V.

You will need a copy ofWarhammer: The Horus Heresy Age of Darkness Rulebookand eitherLiber Hereticus: Traitor Legiones Astartes Army BookorLiber Astartes: Loyalist Legiones Astartes Army Book, all available separately, to use the contents of this book.