When Li Yunmu spoke, demonic energy bubbled forth from his punch, and an even more formidable presence erupted from him, which was extremely close to that of a master god.
The system had said that the yin son of heaven was the son of Yin Emperor who was a quasi true god powerhouse. This kind of person would've certainly given some life saving treasures to his son.
If Li Yunmu didn't use his full strength, yin son of heaven might escape. Then there would be no end to the troubles, so Li Yunmu used his full strength from the start to ensure that the yin son of heaven definitely died.
After it was done, Li Yunmu would kill the five ancient gods and Asura.