The nemesis is a Cerberus sniper specialist. Customized implants allow the nemesis to withstand the crippling kickback of the M-98 Widow antimateriel [sic] rifle, turning a redoubtable opponent into a force capable of inflicting instant death. A suite of high-tech scanning equipment makes the sniper adept at maintaining cover, meaning a nemesis is usually spotted only after opening fire--assuming the target survives the first round.
Because of self-destruct mechanisms that activate upon the sniper's death, the Alliance has never retrieved an example of nemesis augmentation technology. This fact, combined with Cerberus forces' penchant for suicide when faced with capture, has made scientific study of their implants impossible.