Universe 5

Universe 5 is an alternate universe in which evil still exists after the defeat of the Makuta. Most events that deviate from the prime universe's timeline take place after Mata Nui disappeared into the Mask of Life.

Major Deviations from the Prime Universe
Universe 5 has 2 distinct changes in timeline that cause it to branch off from the prime universe.

Makuta Teridax
Within the Universe 5 timeline, Makuta Teridax was always more reserved than his counterpart in the prime universe, and although this had little effect on the fights he had with any of the Toa, it made this Teridax more cautious. In Universe 5, he sees in Karda Nui the potential for his takeover of the Mata Nui robot to fail. Should it be that he remembered the prototype Mata Nui robot on Bara Magna, doubted the competency of his fellow Makuta, or recognized that the Toa he was fighting now had consistently beaten him, he had grown much more unsure of his plan. Because of this, he begins to create countermeasures for this failure. Killing Matoran and expendable Shadow Matoran, he imbues these masks with some of his power, changing their properties and making them infinitely more dangerous masks. He gives these masks to high-ranking Makuta, telling them not to use them until either they absolutely have to or until the plan is about to fail.

To be continued...