- " Rahkshi - shadows that cower in the depths. Exactly as foretold."
- —Turaga Vakama
When a Kraata was exposed to Energized Protodermis, it would die and mutate into inanimate Rahkshi armor. A second Kraata of the same power could then enter the armor and control it. A Rahkshi's power was at least equal to a Stage-6 Kraata's and likely even greater, though it was weakened when separated from the staff that it wielded.
When Rahkshi had no mission from a Makuta to fulfill, they acted as violent and dangerous beasts. But with direction and guidance from a Makuta, they had power enough to overtake even a Toa Nuva. Their violent nature made even Teridax reluctant to send them out, as he knew they would destroy anything in their path.
In addition to their normal powers and those granted by their weapon staff, the Rahkshi could also change into a hover mode. By placing their feet together with the legs stretched forward, they would be able to fly about half a meter over the ground. In this form, the Rahkshi could move much faster than walking or running alone. However, they could not fight, as the weapon staff would have to be broken apart and carried, and attacking could cause them to lose control.
Just like Kraata, there were 43 types of Rahkshi. The best known of these (and the only ones named) were the six Teridax sent to find and take the Avohkii: Turahk, Guurahk, Lerahk, Panrahk, Vorahk, and Kurahk.
- "Their unity will be poisoned, their duty will be broken, their destiny I must shatter..."
- —Teridax planning to unleash his Rahkshi, BIONICLE: Mask of Light.
On Mata Nui, Teridax sent three of his Rahkshi to Mata Nui's surface to stop Takua from finding his destiny. The three travel to Ta-Koro, which ended in the village sinking into the volcano's lava. During this attack, Lerahk fights Tahu, and the Toa of Fire is infected with a poison. The same three then follow Jaller and Takua's path, eventually catching up to them in Ko-Wahi. However, they fail their mission, being frozen in a river by Kopaka Nuva.
Teridax then releases three more Rahkshi, which followed Takua to Onu-Koro. There, they fight Pohatu and Onua, though Onua accidentally causes the entire cave to collapse. Some time during this encounter, Tahu fights Kurahk, and it's anger powers increase the effects of Lehrak's poison, forcing Kopaka to freeze him just to get him out.
At Kini Nui, the Toa Nuva once again encountered all six Rahkshi. Tahu's fire and Lewa's sandstorm create a glass prison around some. Onua then lifts some boulders, which Tahu combines with lava. After dropping them on the few left. Gali then sprays them with water and Kopaka freezes them. The Toa then realize that there is still one more Rahkshi, Turahk. Jaller then sacrifices himself for Takua, and Takua, now realizing his destiny, bears the Mask of Light. Takua then uses his new light powers to defeat the Rahkshi and, using one of the Kraata, finds his way to Teridax on the Ussanui.