Zhang San's abilities, which he almost entirely acquired, were passed down to him in dreams by an elderly grandfather.
However, that grandfather did not seem to have unlimited power, so there were still techniques Zhang San did not know and needed to continuously learn and practice.
These included the Eight Techniques of Hidden Ground which Wei had secretly handed to him, instructing him never to admit that it was he who had imparted them.
Thus, this time Zhang San sought out Wei, partially because it was truly safe to be with Wei,
and partly because he wanted to diligently learn the Eight Techniques of Hidden Ground.
Zhang San wanted to rapidly advance his realm, which required him to fully cultivate the Power of the Five Elements before he could perfect the stage of Five Emperors' Proper Position and step into the stage of Qi Flow Transformation.