Lin Jing, during this investigation, did indeed obtain some useful information.
At the very least, Lin Jing now knew that the disturbance affected only those whose cultivation was below the Divinity Transformation Stage; anyone with a lower cultivation level could not sense it.
If Lin Jing had left immediately after probing the Island Master of True Dragon Island, he might have been misled and made the wrong choices.
Fortunately, Lin Jing was prudent and decided to probe Li Mingwu once more.
Now, Lin Jing knew exactly what to say once the black fog dispersed.
Lin Jing stayed with Li Mingwu for a while, until Li Mingwu began to sit in meditation. Realizing he would not gain any more useful information, Lin Jing left using the Observation Mode.
After leaving the proximity of the Formation Eye where Li Mingwu was, Lin Jing did not hesitate and immediately probed towards the final Five Elements main hall.