The God-Devouring Insect counted as a living being and naturally had its own river of time. However, since entering the Heavenly Demon Palace, it had interacted only with Mu Bai, so changing the direction of its temporal flow was not difficult.
Combining this with the Concept of Time he had comprehended in the Beast Territory, Mu Bai experimented on himself several times while continually pondering his direct temporal connection with the God-Devouring Insect. Gradually, his understanding of the power of time became ever clearer.
I was going to hurry off to save Xing Yun and the others, but since I can control my own time here, why not prepare properly? That will give me a better chance when I go to the Kunling Sect!
After stepping onto the path of cultivation, Mu Bai had experienced many upheavals and changes. His cultivation had advanced rapidly along the way, and what he practiced was exceedingly diverse. He had never had a chance to properly consolidate and sort through it all, leaving grave hidden dangers in both himself and his disposition. Neglecting to refine away his own three demons had led him to commit many acts akin to those of evil demons.
Although his physical body was already extremely powerful, Mu Bai had recently sensed its flaws. Back on Tianmu Mountain, inspired by Tao Hang borrowing power from plants, Mu Bai had shattered himself, allowing the power of the five elements in his bones and flesh to connect with the five elements outside. Although he had succeeded in borrowing external power, the five elements essence accumulated within him had leaked out.
Later, he had detonated his Inner World, shattering all the flesh of his abdomen. Only by accelerating the refinement of the Five Elements Inner Core in his Divine Palace had he regenerated