Lin Mu could tell that Qing Yuan Tiu was going to be one of the finalists and if his guess was correct Enlai Lan would be the other. Unless he fought them first and one of them was eliminated. Lin Mu didn't know how he would fare against Qing Yuan Tiu, as her fighting style wasn't something he had seen before.
If Lin Mu were able to use his abilities, all it would take is a single Blink to eliminate Qing Yuan Tiu. She couldn't move when she used her Gale River Palm and Lin Mu could dodge that easily with a blink. But being here meant that he would have to restrict himself to his sword skills and physical skills.
The Boulder collapsing fist was his most powerful attack, but it was also deadly and was a kill or be killed move. This tournament wasn't meant to be a fight to the death anyway, and thus he couldn't use that either.