[04] Bionicle: Protodermic Evolution (BPEV)

With the Bahrag sealed by the combined might of the Toa, the island of Mata Nui has been saved from destruction at the hands of the Bohrok swarms, but yet another trial awaits. "You cannot imagine what you have unleashed" - just as these final words of the queens ring in the minds of the victorious heroes, they find themselves swallowed up by the ground itself, plunging into chambers of Energized Protodermis, a substance whose supernatural effects change them into more than they were. More than anyone has ever been. Where six Toa Mata embarked into the depths of the nest, now emerge six Toa Nuva, possessing not only new forms and equipment, but also greatly increased elemental powers. But they must soon learn that this does not render them invincible, as those very powers, along with the Nuva Symbols representing them, are stolen by Bohrok unlike any ever seen before. These creatures known as Bohrok-Kal are on a quest to awaken the Bahrag and unleash the destruction of the swarms upon Mata Nui once more, and even with the strength the Toa have gained through their Protodermic Evolution, stopping them will be no easy task.

The first half of 2003 (AKA the filler arc) brings a rematch between the Toa and the Bohrok swarms, both armed with new and greater powers. This expansion covers the Toa Nuva, the Bohrok-Kal, and all things relating to them and their showdown.