Gu Fei was only able to approximately sense an incoming attack through killing intent. There was no way for him to confidently judge the distance of the attack, but he no longer cared about this fact and just swiped his sword while pivoting the moment he felt the enemy's presence behind him.
The sword struck thin air, and he had no idea if he had attacked too early or too late. Nevertheless, he was not flustered by this and just quickly followed it up with another slash. The 17th Form of All-directional Night Combat was supposed to be a technique that allowed the user to continuously attack with a single opening; its focus was to determine the opponent's position after the first move and to continue raining blows resolutely until the opponent was killed, never giving the opponent a chance to retaliate.
