Soul Tower of Trial (18)

They reacted quickly since they didn't bother arguing with Huang Xie.

That was because they could already figure out that he was right.

It really was as he said, the first twenty waves should have been the training session for them and the next nine waves were the real trial. In that case, it was better to build up the defenses as quickly as possible while they still had time.

The ones that had used up most of their energy sat down and started to recover instead of helping with building the defenses.

The ones that were building the defenses didn't mind since they knew that they would need these people to fight the spirit beasts that came.

In a sense, everyone was indeed working together much better than before.

They all knew their roles and they didn't need to exchange words at all to do what they needed to do. 

The main reason why they did all this was because they knew that they wouldn't survive if they didn't work together.