So Fang Zijun did not tell him a fatal point of practice when he was teaching ink to practice leniently. Because of this, Fang Zijun knows Mokuan's level of enchantment, and it may not work.
Originally, he wanted to teach Mokuan to revenge himself, which also helped him. But later, he found that Mokuan's talent was so amazing that he would surpass himself sooner or later. Isn't that a repetition of the cat and tiger story? So Fang Zijun only teaches Mo Kuan something superficial.
To Fang Zijun's surprise, it was unexpected that Mokuan had succeeded in attracting a girl this time, which really puzzled him. More firm can't teach...