The first part of the tribulation was straightforward. Mu Di Bai was a person, naturally he had his own friends and family as well as rivals and enemies. By going under Mu Di Bai's wings, all of those enemies would view him with hostility and perhaps even try to make moves on him in order to strike at Mu Di Bai indirectly.
All of these were tribulations that the current him couldn't face, much less him when he was at the Academy. After all, although he was no longer confident in what Mu Di Bai's cultivation level was, at the very least, he should be in the third set of cultivation. As someone in the third set, or of the Void Returning stage of cultivation or higher, naturally, his enemies would be of a similar stage. For people like these, much less Nascent Soul Stage cultivators, they would have Resonance Stage cultivators under their wings, and each one could easily kill a person like Di Tou with a flip of their palms.
