The general idea was to attract the masters resting behind the portal, kill as many enemies as possible, while creating disarray in the middle of the enemy densely packed ranks!
William kept dashing around, jumping from one point to another, while the enemies tried to catch him without any success. William had no pattern, couldn't be predicted, and his trajectory always surprised the enemies!
On top of that, his true aim wasn't to kill, but to distract! That added more difficulties to his enemies. If he was aiming to kill them, he'd keep relentlessly attacking, not retreating. But this wasn't the case here.
William kept hitting the enemies whenever they tried to rally themselves, then retreated whenever they gathered up on him. His dash technique was so fast, so unpredictable, that made the enemies suffer just to try and direct attacks at him!
