Olisi

"Lesovikk said Karzahni can show you alternate events--usually horrifying ones, intended to terrify you. [...] what if he showed you a future--or a past--that you wished for? And what if you wanted it so much...that you stayed trapped in that vision forever?"

- Sarda, Dreams of Destruction

The Kanohi Olisi was the only Great Mask of Alternate Futures.

History
Initially created by the Great Beings, the Olisi was given to Karzahni after he failed to defeat his brother for the right to wear the Legendary Mask of Creation. Karzahni wore the mask for the next 100,001 years, until he traveled to Mahri Nui and was exposed to the Pit Mutagen. This then fused the Olisi to his face, although he was still capable of accessing its powers.

After Makuta Teridax in the body of Maxilos destroyed Karzahni's sanity, Karzahni used the Olisi's power to trap Lesovikk in a vision of an alternate timeline where his team had never died. Despite the lure of the dream and initially believing it, Lesovikk eventually realized that he was trapped in an illusion. This realization was then enough to allow the Toa to force his way out of the Olisi-created halluciation.

After Teridax in the body of the Great Spirit was killed by Mata Nui, Mata Nui used the powers of the prototype robot and the Ignika to unmutate those affected by the Pit Mutagen. Karzahni was included in its range of effect, unmutating himself and the Kanohi Olisi. Later, Karzahni died a mysterious death on Spherus Magna, leading to his body falling off a cliff. The Kanohi Olisi was broken upon his impact with the ground.

Powers
The Kanohi Olisi gave its user the power to project a mental vision of an alternate timeline or a possible future into their and one or more being's minds at once. The user could use their thoughts or thoughts of the victim(s) to create the vision; the user will also share in the created vision. While the user could place a vision in a target's head and leave it alone, this made it easier to free oneself from the vision. Karzahni tended to activate the Olisi's power through an energy blast aimed at his target(s). It seems that the user does not control exactly what is seen, as several times Karzahni gave visions of events he could not know about. Rather it seems that he simply dictates whether it will be a pleasant vision or a nightmare, and the victim's own mind and memories create the details.

Example Usages

 * In BIONICLE Legends 2: Dark Destiny, Karzahni used the Olisi to give the Ta-Matoran Jaller a vision of an alternate timeline where he had not saved Takua during their searching for Toa of Light. Karzahni later used the Olisi again to create a vision of a possible future of what would happen if Mata Nui died.
 * In Dreams of Destruction, Karzahni planted a vision in Lesovikk's mind of an alternate version of his past. However, since Karzahni did not continually focus on the Toa, Lesovikk was eventually able to break out of the mental illusion.

Great

 * Karzahni - Formerly; mask briefly fused to face while affected by the Pit Mutagen until Mata Nui cured him. Karzahni now deceased and Kanohi broken.

Olisi