He began to feel the toll of losing a large amount of inner energy rapidly on his body in lesser duration.
He's psychologically more tired than physically. As every drop of inner energy was consumed he began to feel heavy in his heart and mind thinking whether he will win or not.
After four minutes Lang Fu began to feel heavy physical tiredness with inner energy being used fully. Even then he tried to stand against the monster for a few more minutes.
But the monster fought at the same pace from beginning to end without showing an ounce of tiredness.
So Lang Fu fainted from tiredness and fell on the ground accurately at thirteen minutes.
The three side guards came forward and engaged with the monster to stop it from attacking unconscious Lang Fu and killing him.
Using the chance given by three guards Dong Li used this chance to come forward and took Lang Fu back.
