Su Yu was leading the [Howling Moon Wolf King] towards the direction of the cliff.
However, the process of luring a creature was not as simple as "release spell + run away". It involved a high level of technical skill, especially when dealing with a boss creature that possessed a degree of intelligence.
As Su Yu had entered the [Howling Moon Wolf King]'s threat range, he noticed the Wolf King didn't attack him. Instead, it gave a seemingly "confused" expression that felt almost anthropomorphic.
Through this expression, Su Yu deduced that the Wolf King was rather intelligent.
And, with such intelligence, these boss characters would not hesitate to leave once they felt like they stood no chance of catching their enemy, or when their health was critically low and they believed they could be defeated.
Therefore, Su Yu had to put on a believable "performance" while leading the Wolf King to the cliff.