The planet of Cthonia, once home of the Sons of Horus, is consumed by a rolling war and under siege by the Imperial Fists. The True Sons of Cthonia vow to retake their world before the Warmaster claims Terra, with the aid of the Word Bearers and the Alpha Legion.
Standing between the traitors and victory is a garrison of Imperial Fists, reinforced by warbands of the Shattered Legions and even a cadre of Loyalist Thousand Sons.
This 240 page hardback rulebook includes eleven new missions based on the events of the siege of Cthonia, and campaign rules to fight the siege from beginning to apocalyptic end.
Also included are rules for new loyalist and traitor characters, and for new units including Astartes Inductii, Legiones Decurions and Cults Abominatio.
—description from the publisher