The Dark Troopers were advanced battle droids and infantry exoskeletons that featured heavy plating that resembled the armor of a stormtrooper, powerful weapons, and jump packs for increased flexibility and tactical advantage.
Besides the Phase Zero prototypes, they came in three versions: the Phase I dark trooper was a skeletal droid armed simply with a vibroblade and physical shield, primarily a testbed for the later stages; the Phase II dark trooper, which featured, in addition, the external elements; and the Phase III dark trooper, which was the main unit and was never fully developed. Only three Phase III prototypes were on board Arc Hammer. One of these was used by the originator of the project, General Rom Mohc. It was a more powerful variant of the Phase II model and was able to be worn as a battle exosuit.