Exo-Toa

Exo-Toa were special suits of powered armor invented by the Nynrah Ghosts engineers. Toa and other similarly-sized beings could wear and control them, or they could be programmed to act on their own as robotic sentries.

History
After the Makuta species evolved from biomechanical form to a purely gaseous state, Chirox took over an Exo-Toa to "demonstrate" to Mutran the new powers antidermis exhibited. Exo-Toa were one thing Makuta could possess along with other robots, such as the Maxilos Robots. Later, when Mata Nui fell into his deep sleep, the resulting Great Cataclysm ruptured a Makuta's armor, and needed to be placed in an Exo-Toa suit in order to remain alive.

In the time of the Toa Hagah/Rahaga, the Brotherhood of Makuta used Exo-Toa as part of their army, which also included Visorak, "Fohrok" and their Dark Hunter allies.

The Bohrok War
Thousands of years later, when the Bohrok swarms were awakened by Teridax to attack the island of Mata Nui, the Toa Mata ventured into the Bohrok Nest to confront the swarms' twin queens. Travelling through the tunnels deep below the island's surface, the Toa discovered a chamber containing six Exo-Toa. Each Toa stepped into one of the suits, which they then attempted to use when they encountered the Bahrag. However, Tahu found that the electro-rockets had no effect on Cahdok and Gahdok; even worse, the armor hindered the Toa from using their elemental powers. Only by abandoning the suits were the Toa able to successfully defeat the Bahrag.

The Bohrok-Kal Crisis
Later, when the elite Bohrok-Kal tried to free the Bahrag, the now-Toa Nuva followed the Bohrok-Kal into the Nest; there, they found the six Exo-Toa fighting the Kal on autopilot. However, the battle was a short one, and the Exo-Toa were reduced to scrap metal. However, after a last-minute gambit on Gali's part, the Bohrok-Kal's powers spiraled out of control; Gahlok-Kal, whose power was Magnetism, ended up drawing the Exo-Toa pieces toward itself, crushing the Bohrok-Kal under the wreckage. Later, Nuparu, an Onu-Matoran Engineer, salvaged the scrap, intending to study it; however, he had little time to do so before he and five other Matoran embarked on a journey to Voya Nui and subsequently became the Toa Inika.

Reign of Makuta
During Teridax's reign, Exo-Toa were used by Makuta to hunt down and apprehend fugitives and return them to Metru Nui. One such army of Exo-Toa attacked Tahu's team in the ruined land of Karzahni; fortunately, Onua arrived in time to save them, and destroyed the robotic suits with an earthquake.

Set Information
''When a Toa dons the Exo-Toa armor, he wield more power than any being on Mata Nui hs ever known! Hidden underground for centuries, the Exo-Toa features a mighty claw arm and an awesome electro-rocket. But will even the energies of the Exo-Toa be enough to overcome the challenge of the Bahrag?''
 * The set number was 8557.
 * The set consisted of 360 pieces.
 * The set allowed four Toa Mata sets to fit into it: Tahu, Gali, Lewa and Kopaka. The Onua and Pohatu models needed to be modified in order to fit.

Appearances

 * Comic 6: Into the Nest - First appearance
 * Comic 7: What Lurks Below
 * Comic 8: The End of the Toa?
 * Comic 11: A Matter of Time...
 * Comic 12: Absolute Power
 * BIONICLE Chronicles 2: Beware the Bohrok
 * BIONICLE Chronicles 3: Makuta's Revenge