That's right. Strengthening drug!
Su Ling could be so heavenly defying precisely because of Zhang Zhongtian's black market strengthening drug. After achieving the perfect balance of the side effect, it allowed Su Ling to improve her physical fitness by leaps and bounds before the exam! This was why she was easily able to kill the tiger!
Compared to Su Hao, her current physical strength is multiple times stronger!
This was also the reason why Su Hao was here.
From the moment he came back, he already made a plan to create an all-out strategy so that Su Ling would be famous worldwide!
As for the reason behind it?
Su Hao's reason was pretty simple.
In the future, if anyone has any desires to make a move on Su Ling, they would first weigh whether they're qualified or not. If Su Ling can gain a world esper's attention and become their disciple...
It can be counted as fulfilling one of Su Hao's wishes.