Encased in the same Travel Machines as their predecessors in the Fifth Generation, the drones were the product of the mutation of humans transported to the growing fleet by the Scientists under the direction of the Emperor. Ingrained with the usual sense of Dalek superiority, this Generation loathed itself – they were not of Kaled stock and therefore were impure and inferior to the Daleks. And yet, Daleks they were. This paradox drove the entire race insane, making them willing participants in the Emperor's new religion.
During the course of the Emperor's descent into madness, the Dalek Command Structure was abolished. Those surviving high ranking Daleks were re-assigned as Elite Guards for the God-Emperor. Unswervingly loyal, the guards accepted the Emperor's doctrines and visions of an Eden for their race.
Encased in Mark Five travel machines, the Elite Guards were distinguished from the standard Dalek drones by their black domes. The power plant within the casing was enhanced, allowing these Daleks superior firepower to regular units. In all other ways, the guards were identical to the hundreds of thousands of drones that had been produced by the time the Emperor was forced to move against Earth by the Doctor's intervention.
