Kralhi

The Kralhi were Nuparu's first attempt to create law enforcement robots for Metru Nui. They were scorpion-like machines whose tails could produce and fire energy spheres to imprison a target. The sphere then drained the victim's energy until they passed out, directing that energy back to the Krahli. However, this proved an inefficient method of stopping lawbreakers, as the goal was to render them unable to cause trouble and get that back to work as soon as possible, but victims of the Krahli would need be unable to work for days as a result of the energy loss. Therefore, the Kralhi were deemed a failure and discontinued. The Matoran attempted to scrap them, however, they resisted. With the help of the newly-created Vahki, the Matoran were eventually able to drive the Krahli out of the city. They took up residence in one of the large waterways leading to the island above. Much later, when the Onu-Matoran Archivist Mavrah left the city with a group of ancient, enormous Rahi, he encountered the Krahli. At first, he was afraid they would attack him; instead, they still seemed to be driven by the programming of their original mission: to serve and protect the Matoran. For years, Mavrah, the Krahli, and the Rahi lived in peace, until the Toa Metru came through the waterway bringing six Matoran to safety. Mavrah, who knew nothing of Makuta's attempted takeover of Metru Nui, assumed the Toa had been sent by Turaga Dume to bring him back, and ordered the Krahli to capture them. A lengthy three-way battle ensued between the Toa, the Krahli, and the Rahi, which was further complicated by the arrival of several dozen Vahki. In the end, all the Krahli were destroyed, Mavrah killed, and the Rahi driven back into the lake. The Toa then trapped the remaining Vahki under a rockslide and continued on their journey.

Trivia

 * Kralhi could be built as a combiner set consisting of Onewa, Vakama and Matau