Chen Ming had acquired a martial ghost technique from the spirits.
The Spirits felt depressed not because something bad happened to them but because they had been practicing the martial ghost technique for hundreds of years. They practice it since they died after battling demons.
But Chen Ming was able to master it easily. How could they not be depressed?
Were they worthy enough to be under him?
Chen Ming didn't always need scriptures. Just by listening to the correct training method, Chen Ming was able to practice it. The system then recognizes it as a skill. It was really cheating.
Chen Ming had obtained the Martial Ghost Technique. It allowed Chen Ming to cultivate his mental power and spiritual energy.
The Mission was completed, and Chen Ming leveled up another ten levels. Chen Ming becomes stronger very fast. If it continues like this.
It didn't even take a year for him to reach the Martial Ancestor Realm.