The reason why Zhao Hai revealed the liquid silver was to prepare for the future. He was very clear that he had not taken any medicine at all. Although everyone thought that he had taken medicine now, when the time came for the competition, whether he had taken medicine or not would naturally be exposed. At that time, he would have to come up with a reason to let everyone know why he was so strong.
Liquid silver was the best reason. Liquid silver was very famous, not only in the array world, but even in the cultivation world. Zhao Hai's reason was very convincing.
