Calculation, it's all calculation!
Emperor Ziwei's scheme is actually very simple. Didn't Xuanzang make a vow to resolve the disaster caused by the demons breaking out from the underground prison?
Then, I will simply hide the Feidan.
This way, it can obstruct his vow, naturally causing the entire Journey to the West to come to a halt.
By doing so effortlessly and going with the flow, it can add another trial on the path of the Journey to the West for Scriptures, why not?
This action of mine is much easier than what Empress Qinghua and Emperor of Longevity did before.
And then? When Xuanzang and the others get anxious and can't find the Feidan, I will rely on the sensing left on the Hidden Dragon Pearl to tell them the whereabouts of the Feidan.
In this way, not only can I help them overcome this calamity, but I can also earn great favor from the Journey to the West Pilgrimage Team, why not?
