Lu Yuwen was helpless. It wasn't like there was no counter to a Knight's taunting skills, but Blade Masters had no such method. Lu Yuwen could only quietly watch as his Flowing Cloud dashed towards the Knight. The Knight couldn't avoid the attack, but he was able to disrupt the enemy's rhythm. Taunt skills were quite useful, even in PvP.
Roar wasn't a skill limited by time. The target had to hit the target at least once in order to dispel Roar's effects. This Knight was quite smart. After roaring, he immediately ran in the other direction. He clearly wanted to delay Lu Yuwen from doing anything for as much time as possible. Lu Yuwen obviously knew what Roar did. Since he had no way of dispelling the effects on his own, he actively chased after the Knight. He used Triple Slash to close the distance and his sword flew towards the fleeing Knight.