Inside this 240-page hardback book you'll find:

- The Years of Darkness and Blood – An in-depth exploration of the bitter and futile wars that raged across the galaxy in the last days of the Horus Heresy including a detailed timeline
overviews of all Loyalist and Traitor forces the rise of the Legiones Inductii and the full narrative of the world-shaking Siege of Cthonia.

- Campaigns of The Age of Darkness: The Siege of Cthonia – A full Onslaught Campaign system providing rules for a linked series of games between 2-6 players where each victory or defeat
builds up to a final battle. Also included are specific rules to tailor your Onslaught Campaign to the Siege of Cthonia.

- Age of Darkness: Core Missions – Five new Core Missions balanced for both campaign games and Matched Play events. Race to claim vital strongpoints in Sudden Strike adapt to shifting tides
in Strike and Fade or battle for the central ground in The Heart of Battle.

- Siege of Cthonia: Apex Missions – Two new Apex Missions with extensive special rules intended for campaigns and narrative games. Fight through an ill-fated orbital assault of grav-mines and
dropship hulks in The Pyre of Ambition and survive an ambush from underground bunkers in The Ashes Of Victory.

- Age of Darkness: Zone Mortalis – Full rules for Zone Mortalis games smaller-scale battles of Warhammer: The Horus Heresy fought within cramped war zones such as disputed spaceports
besieged hive cities and winding fortress tunnels. Includes extensive rules for terrain and visibility deployment and reserves Reactions and Objectives and army selection.

- Zone Mortalis: Core Missions – Three new Core Missions and two new Apex Missions for Zone Mortalis games plus specific rules for Cthonian Underworld Zone Mortalis terrain such as
Subterranean Tunnels and Promethium Condenser Tanks.

- Legiones Astartes: Rules Addenda – Extensive additional rules units and upgrades for use by the Sons of Horus Imperial Fists and all Legiones Astartes armies including:
– Legiones Astartes: Imperial Fists – Wargear and Warlord Traits for Imperial Fists armies and a profile for Lord-castellan Evander Garrius the Tyrant of Cthonia.
– Legiones Astartes: Sons of Horus – Wargear and Warlord Traits for Sons of Horus armies and a profile for Vheren Ashurhaddon the First Reaver.
– Legiones Astartes: Legiones Decurion – Legiones Decurion rules for skilled tank commanders including two Decurions for all Legions and one each for the Imperial Fists and Sons of Horus.
– Agents of the Cults Abominatio – Rules for fielding Cults Abominatio Operatives in Traitor armies including a profile for the Infernus Abomination.
– Legiones Astartes: Inductii – Rules for fielding Inductii the hastily-created Astartes used as reinforcements in the latter days of the Horus Heresy with specific rules for each Legion.

- Showcase – Along with atmospheric photography and annotated artwork the book includes a showcase of beautifully painted miniatures for the Sons of Horus Imperial Fists Traitor Allies and
Loyalist Allies.