Great Cataclysm

The Great Cataclysm was the effect of Makuta Teridax making Mata Nui fall asleep.

Background and Prelude
Teridax, the leader of the Brotherhood of Makuta, an organization dedicated to serving Mata Nui and protecting the Matoran, had begun making plans to take control over the Matoran Universe, inspired by the League of Six Kingdoms. To do this, he planned to infect Mata Nui with a virus, causing him to fall asleep.

300 years after the Brotherhood attacked Mata Nui with a virus, when Mata Nui passed Aqua Magna on his way to where Spherus Magna once was, he went into a coma.

The Great Cataclysm
When Mata Nui went into a coma, he fell towards the nearest planet, Aqua Magna. When Mata Nui hit the ground, the whole Matoran Universe suffered from an earthquake.

Aftereffects


The earthquake of the Great Cataclysm caused some land to break away from the Southern Continent, and to blast onto the suface of Aqua Magna. How the piece of land managed to launch up onto Aqua Magna was unknown. This land would later be called Voya Nui, which would become a broken, stormy land only notable because of the Mask of Life, Ignika, in its large volcano.

The impact of Mata Nui's fall damaged his camouflage system, although it still functioned at the time, and caused the creation of the island of Mata Nui. Energized Protodermis also leaked when the camoflage system damaged, resulting in 6 reigons to be created on the island, each with a different climate.

The earthquake also damaged The Pit, causing in the release of the prisoners, caused a hole in the Universe Core ceiling that would allow Pit Mutagen to leak on the floor of the Universe Core, resulting in the creation of the Swamp of Secrets, the creation of the Stalactite Villages, resulting in the Av-Matoran returning to the Universe Core, and damaged other areas in the Matoran Universe.

While Mata Nui could not or would not prevent the devastating attack, he made sure that heroes would come to restore the worst of what was lost:

The most immediate matter was that the Matoran in Metru Nui had to be evacuated safely out of danger. Fortunately, Mata Nui's choices for Toa Metru did not fail him, though it was not an easy task: Teridax had summoned the Visorak hordes to invade Metru Nui, and Toa Vakama's overconfidence led the team to be mutated into half-beast Toa Hordika. However, in the end, the Toa were cured of their mutation and the Matoran were safely relocated to the tropical island above the city that the Toa had discovered and named "Mata Nui", in honor of the sleeping Great Spirit. Once there, the Toa Metru gave up their Toa power to wake the Matoran from their stasis, becoming Turaga. But their victory had come at a price - Teridax had been freed from his prison, and would certainly be back.

Another preparation made before the Cataclysm was that the Toa Mata entered Toa Canisters that would bring them to the island of Mata Nui, so they could begin the task of reawakening the Great Spirit. However, the canisters malfunctioned and were left drifting in the sea for a thousand years. In this time, Teridax indeed returned, enslaving the Rahi wildlife and constantly having them attack the Matoran, in order to keep them near the safety of the villages and away from Metru Nui. Meanwhile, Turaga Dume, Keetongu, and the Rahaga (who had been allies of the Toa Hordika) stayed in Metru Nui and did what they could to begin restoring the city.

Eventually, a Matoran named Takua gathered the Toa Stones that the Toa Metru had once made, and bringing them together shot a beam of light into the sky that finally summoned the Toa Mata to the island. These stones would later be used as Toa representatives in the Amaja circle. Since then thier status has been unknown. The Toa Mata would challenge both Teridax and the Bohrok swarms that he awakened, becoming Toa Nuva in the process.

However, defeating Teridax was not the Toa Nuva's destiny, that honor belonged to another. Takua discovered the Avohkii Mask of Light, an ancient Kanohi mask said to belong to the Toa of Light who would defeat the darkness. After a journey of self-discovery, Takua realized that he was the prophisized hero, he put on the mask and transformed into the Toa of Light, renaming himself Toa Takanuva (short for tak u a nuva). He went to challenge Teridax himself, and in the course of the battle the two fell into a pool of Energized Protodermis, emerging as a single being called Takutanuva. As Takanuva had superior control and Teridax did not, Takutanuva then reopened the gateway to Metru Nui, letting the Matoran return to their city home. Afterwards, Takutanuva was crushed by the giant gate, Takanuva was quickly revived but Teridax was presumed dead by the Toa Nuva. However, Takanuva was not sure of the finality of Teridax's defeat; while fused with Teridax, he got the feeling that there were bigger plans at work, ones that the Matoran's return to Metru Nui would not stop...

When the Matoran of Mata Nui returned to Metru Nui, Turaga Dume revealed that he had discovered that the attack on Mata Nui was indeed deadly, and the Great Spirit was mere days away from dying. If Mata Nui were to die, the universe would die along with him. Dume sent the Toa Nuva to Voya Nui to find the Ignika Mask of Life that could possibly save the Great Spirit's life, but they ran up against a group of Piraka ("thieves and murderers") who were also looking for the mask. But it seemed that, again, it was not the Toa Nuva's destiny to claim the mask - six Matoran followed the Toa to Voya Nui to give their help, but they were struck by lightning from the mysterious Red Star and changed into Toa Inika.

The Toa Inika recovered the Mask of Life, but it escaped from them and plunged underwater, to Mahri Nui, an underwater Matoran city under attack by the Barraki warlords, banished to the Pit beneath Mahri Nui long ago, and freed by the Great Cataclysm. The Inika themselves were mutated by the Water's Mutagen, becoming Toa Mahri.

However, Mata Nui was not the only one with backup plans, the Brotherhood of Makuta made some as well. According to records that Zaktan found, if the Matoran were able to escape Mata Nui then they would eventually join with Toa, and if the Toa could not be eliminated: let them win. Let them wake the Great Spirit. Even let a Makuta die, if that was what was needed. It would all only serve to help bring about the Brotherhood's ultimate victory. As it turned out, the Brotherhood were relying on this during the whole plan. As revealed after the Toa Nuva left Karda Nui by none other than Teridax himself, he needed the Toa to revive Mata Nui. Just before he was revived, Teridax entered a underground chamber under the Coliseum, which held Mata Nui's brain. Before Mata Nui was ressurected from death, Teridax forced himself into the body of the Great Spirit, and later forced Mata Nui into the dead Ignika, which had been used to revive him, and banished him out of his own universe.