YinKong stopped the Air Waves attacks then circled around Xuan with her speed advantage. She couldn’t break through his defense but neither could he attack her when even raising his arm was a difficult task. That was the reason YinKong hesitated in using that attack.
The light surrounding Xuan exploded while she hesitated and took away her chance to use the attack.
YinKong felt the air solidified and she was frozen in place. The light from the Lambda Driver had spread beyond her, which meant she was within attack range.
(Converging to the Xuan in reality… does that include intelligence?)