The person who lured out the officers on the 'Flying Glory' corrupted by Jian Qi was, of course, Gu Jing, who had a Magic Lord of Thousand Changes as his 'advisor'.
It's not very realistic to use his Magic Lord of Thousand Changes to deceive extremely high-level beings. After all, his Magic Lord of Thousand Changes has only one appearance. Its nature in the Subspace was washed by Gu Hang.
In the eyes of some Great Demons of the same level, the distinction is very obvious. They can easily discern that the entity before them has only the appearance and is completely different in essence from a real Magic Lord of Thousand Changes.
However, to deceive those not at such a high level, it is quite effective.
Ordinary people can't really identify things like Subspace essence.
