Aghoru

Aghoru is a Thousand Sons compliance world in Ultima Segmentum, the dry fifth planet catalogued by the 28th Expedition as Twenty-Eight Sixteen. Compliance, in Imperial usage, is the incorporation of a world into the Imperium. The primitive clans of Aghoru called the earlier builders of the planet Elohim and regarded an artificial mountain as a prison for spirits.

Magnus remained to study the Mountain while Leman Russ waited in the Ark Reach. Revenant Titans possessed by daemons, together with the daemon Choronzon, turned the attempted diplomacy into a battle, and Magnus resealed the corrupted webway knot. After the events at Prospero, a martial fragment of Magnus built a colosseum on the planet until hunters confined it within Lemuel Gaumon. A fleet then burned the surface.

Aghoru remains significant as the opening setting of A Thousand Sons. Unofficial summaries place it in Ultima Segmentum, retain the 28-16 designation, and distinguish it from Prospero and Sortiarius.