My guess, in the show setting would be Shen Wei either wanted to relieve pressure or check how much time he has, aka, how well his already limited powers above ground function with the added layer of light energy mixing in.

Ooh, yeah, excellent point! He might well be checking how it's progressing -- or he might have intended to, anyway. He's so weakened afterwards that, if it was deliberate, something must have gone terribly wrong, I think.

It's actually hilarious that An Bai and his friends been to Ye Zun’s Pillar before and stuff. They put a Ye Zun supporter on the throne.

Hm, I don't think An Bai and friends were converted to Ye Zun's side that first time? They didn't actually speak to him then -- they were too busy chasing Zhao Yunlan. (And Da Qing manages to lurk around the pillar without being converted, so that must be possible.) I think the friends were converted later on in this ep, when they started chanting about revering the night, and An Bai never was. The Regent knew An Bai was a criminal, though -- it was his and his friends' death sentences that were used as leverage to get him onto the throne.

Ye Zun is waaay too good at mind-control. To me, that's the creepiest thing about him. /o\