The Perditha Sub-Sector is an area of Imperium space that lies in the far reaches of the Ultima Segmentum. In the aftermath of the Great Rift's creation Perditha was invaded by the forces of Nurgle and when the Sub-Sector began to be overwhelmed, the warhost of the Alaitoc Autarch Cynbel Shadespear appeared. In order to prevent Perditha's fall, the Autarch led a daring attack that awoke the slumbering Necron on the moon of Ull and then led them to the battlefield that Perditha had become. Now the Sub-Sector is engulfed in a war between the Imperium, the forces of Nurgle and the Necron. And in the background, the Rangers and Pathfinders of Alaitoc are everywhere and make their presence known, by arriving after major conflicts to finish off the victor's depleted forces.