Rorzakh were the Vahki model assigned to Onu-Metru on Metru Nui. Rorzakh were relentless, willing to continue a pursuit even to their own destruction. Their Staffs of Presence allowed them to see and hear whatever their target saw or heard.
Even outside of Onu-Metru, Rorzakh were known for being particularly relentless in pursuing their targets, unwilling to give up the chase. There was no risk they would not take to get their job done. There was even a story that a Rorzakh had once plunged into a mine shaft, in free fall, to try and catch a lawbreaker.
Rorzakh's zone of control was Onu-Metru. They were equipped with Kanoka disks and the Staff of Presence, which allowed the Vahki to receive audio and visual input from a target for the duration of effect without the target being aware. They were relentless and fearless. Their preferred tactic was to pursue anywhere, for any length of time, no matter the danger.
According to whenua, in all of their history, the Rorzakh never failed to capture someone who tried to run away from them. They never gave up the chase.
Rotating squads of Rorzakh and Zadakh provided security for the Coliseum storage room.
Vahki Rorzakh subdued Rahi which broke free of their stasis tubes in the Archives.
Rorzakh had the important job of protecting the Archives. They were the most relentless of the Vahki, never giving up on a chase. Rorzakh Staffs of Presence had the longest-lasting effects, allowing the Vahki to see and hear whatever the affected Matoran did without the Matoran being aware of it.
Matoran who were affected by Rorzakh's power would unknowingly lead said Rorzakh to any co-conspirators, allowing the Vahki to arrest all of them at once. This would scare them into going back to work because they knew they couldn't get away with anything.
Rorzakh did not verbally communicate with the Matoran they spied on, their power let them see what the Matoran saw and hear what the Matoran heard, and therefore they knew everybody the Matoran saw and talked to. The Matoran being spied on would be unaware that this was happening.