Following on from events of The Master of Mankind [SPOILER WARNING], Chris Wraight’s Horus Heresy short story Magisterium tackles the Adeptus Custodes as they regroup following the appalling losses incurred in the Webway War. It follows one of the few survivors, Samonas, as he comes to terms with the changed status of the Custodes, watching on while Constantin Valdor clashes with Rogal Dorn over their place in the war to come. Interspersed with recollections of the fighting on Prospero, it’s a powerful story of the differences between the Custodes and the Legiones Astartes, and the preparations taking place on Terra.