When Lu Sheng attained the eighth stage, the divine ability evolved from the Eternal Ash Emperor's Authority was Devouring Heaven and Earth!
This divine ability serves many purposes. It can be used like a divine killing art, gathering the devoured power to unleash terrifying strength.
At the same time, this divine ability can also be used for cultivation.
By devouring all the energy between heaven and earth, it can enhance one's own cultivation efficiency!
Lu Sheng's clone in the Martial Arts Realm, after breaking through the sixth stage, could already channel a portion of the main body's power. In such a situation, even if it couldn't unleash the full power of Devouring Heaven and Earth, it could still mobilize some of its traits.
Hence...
Lu Sheng could directly devour others' cultivation, thereby enhancing his own.
Although some power is lost in the process of devouring and refinement, it's still much faster than Lu Sheng cultivating on his own.
