Nui Stone

"The Nui Stone is active, where a Toa Stone is passive. It doesn’t wait for you to give it your energy – it takes it. Once activated, it will absorb minute amounts of energy from any Toa within a 3000 Kio radius, so slowly and surely that it won’t be noticed until it’s too late. Then that energy can be absorbed by a living being – can you imagine? One being with the power of dozens, maybe hundreds of Toa, or more?"

- Toa Tuyet to Toa Lhikan, The Many Deaths of Toa Tuyet

The Nui Stone was a powerful one-of-a-kind artifact, with the aggressive tendency to slowly absorb Toa energy from all Toa in a 3000-kio radius. Whoever touched it would gain its power. It glowed red with energy and heat.

Creation
Long ago, the makers of the Nui Stone created it, but knowing its power, decided to destroy it. However, before they could, it was stolen from them and passed around for years.

Tuyet's Home Island
At some point, the Nui Stone ended up on the home island of the Water Toa Tuyet. The Dark Hunters came after it, but they arrived to find that the stone was gone...as was Tuyet. Naturally assuming she had taken the Nui Stone with her to Metru Nui for safekeeping, they went there.

Metru Nui
On Metru Nui, Tuyet hid the Nui Stone in her dwelling and kept it a secret for a long time. Eventually, deciding the Dark Hunters would not stop looking for her if someone did not stop them, she began to murder Matoran, claiming to Toa Lhikan and Nidhiki that it was a 'countdown' by the Dark Hunters, and that she had seven days to give them the Nui Stone. While Dark Hunters were indeed searching for her, they had no idea of such a countdown. Lhikan realized that Tuyet had been the murderer, and used his heat-sensing abilities to locate where she had hidden it.

Tuyet took the Nui Stone back from Lhikan and used it to empower herself, claiming that she would become the 'ultimate solution' and do what the League of Six Kingdoms tried to do. Lhikan and Nidhiki defeated her, however, then Nidhiki tried to use the Nui Stone for his own gain but before he could, Lhikan destroyed it so Nidhiki wouldn't make the same mistake.

The Pit
Millennia later, Toa Mahri Matoro and Teridax (in the body Maxilos) were exploring the ruins of the Pit, looking for the remains of Tuyet. She had been sentenced to the Pit shortly after the incident with the Nui Stone and had died there in the Great Cataclysm.

After finding her body, Makuta ordered Matoro to use his Great Tryna to give Tuyet artificial life, claiming that Tuyet could help him recreate the Nui Stone. Matoro protested that she would have no mind when she came back and would not be able to help, but went along with Teridax anyway. As it turned out, Tuyet had very small fragments of the Nui Stone still embedded in her armor. Teridax revealed that he could recreate the entire Nui Stone from this fragment, given he had another powerful artifact; the Staff of Artakha. However, Brutaka then took it from him and gave it to Botar.

As for the stone, the 'real' Tuyet was removed from the universe by the Order and replaced by another Tuyet from a different universe with fake Nui Stone fragments embedded in her armor. The remains of the stone were still embedded in her armor while she was held by the order in an attempt to pry the secrets of how to create their own stone out of her for over 1500 years. She managed to convince one of her guards of her innocence however and helped her fake her death by disintegration, which resulted in the Oder not attempting to search for her.

Reign of Shadows
It took her 2000 years to find her way back to her home universe, and once she did, she found herself in the Metru Nui Archives after Teridax's takeover, where she was found by a group of Matoran who had no idea of her true identity. She had somehow reassembled the Nui Stone and intended to take over the universe.

Dark Mirror
In the Dark Mirror alternate universe Tuyet took the Nui Stone and killed Lhikan and later formed the Toa Empire.

Trivia

 * The Nui Stone was first revealed in the BZPower-exclusive short story The Many Deaths Of Toa Tuyet.

Nui-kivi