BIONICLE Adventures 6: Maze of Shadows

Maze of Shadows is the sixth Bionicle Adventures book and came out 2004.

Story
The Toa Metru landed on the island that would soon be known as Mata Nui. Each of the Toa explored it and found a place to build their Koro(village).

While deciding on a location for Ta-Koro, Vakama, Toa Metru of Fire, had a vision in which his Toa powers disappeared. Thus, he and the other five Toa Metru gathered six stones, investing some of their energy into it. Soon after, Onewa, the Toa Metru of Stone, found a tunnel entrance that he believed would lead back to Metru Nui. The Toa Metru entered the tunnel, and soon encountered a nest of sleeping Bohrok, during which Vakama had a vision of the Bohrok destroying the island above.

The Toa Metru also came across a mechanical creature called a Kranua, which they defeated. But as they moved on, they were attacked by mutated Rahi and a Rahi Nui. During the battle with the Rahi Nui, Nokama, Toa Metru of Water, was poisoned and fatally wounded. While the Toa argued about whether to bring her to Metru Nui or back to the island above, Morbuzahk-like vines came out and grabbed the Toa Metru. The vines didn't belong to the Morbuzahk, but to a prototype named Karzahni, which had been discarded because it was too willful and stubborn. The Karzahni offered to heal Nokama if the Toa Metru would retrieve it some energized protodermis, which was the substance that mutated the Rahi.

The Toa Metru took some of the energized protodermis after defeating the Energized Protodermis Entity. Which they gave to Karzahni, but as its destiny was not to be transformed, it died.

Soon after, the Toa Metru encountered a large body of water which they could not cross. Due to that, they took the remains of Karzahni and built a boat out of it, which Vakama christened the Lhikan 2. The Toa Metru then sailed this boat back to Metru Nui.

Characters
Toa Villains
 * Vakama
 * Nuju
 * Whenua
 * Nokama
 * Matau
 * Onewa
 * Energized protodermis entity
 * Rahi Nui
 * Karzahni
 * Kranua