The Tai Chi was a mutated one-eyed giant beast. That was an extremely rare type of Heaven and Earth Spirit Beast. That beast was born in the Chaos and was born with the law of earth in its veins. It was able to control the earth with ease and when it matures, it would be able to possess power equivalent to that of a True Immortal.
There was one thing special about that beast, that was its single eye would occasionally undergo some kind of mutation, giving birth to a power of time that would drive all Immortals insane. However, there were very, very few such mutations, with less than one in ten thousand. Every time such a mutation occurred, chaos would ensue in the local area.
The Time law was one of the three supreme nomological laws, alongside the Space Law, and Samsara Law in the Three thousand Laws.