Yun Yudie always believed that Lu Chen apprenticed under Heavenly Language Immortal Venerable with selfish motives; since he had intentions towards the Heavenly Language Immortal Venerable, he would not just stand by and watch her go to the Northern Domain to face certain death.
So, he was likely to impart the Divine Light Thousand Lamp Scripture, an Immortal Law capable of subduing Heavenly Demon Power, to the Heavenly Language Immortal Venerable.
However, if the Heavenly Language Immortal Venerable mastered this Immortal Law, it would mean the entire Mysterious Moon Palace would master it as well. Once this Immortal Law gets disseminated, more and more people would be capable of subduing Heavenly Demon Power, making the days of the Demon Emperor difficult.
The Demon Emperor was also an old acquaintance of Lu Chen, which made the situation for Lu Chen like a dilemma between two loyalties.
