Creating Mysterious Techniques wasn't an easy task, as it involved many things like proper knowledge and understanding of the related Affinity, what Qi pathways to use, and other factors.
And most of all, a Cultivator's comprehension needed to be high for that.
Fortunately for Ye Jun, he checked all of those boxes. His comprehension was very high, he had a good understanding of the Dao of Fire because of his adventures in the Fire Hall, and Grand Genesis Foundation Sutra helped him have a good understanding of Qi pathways and the way Qi circulated in them.
All of this led to him creating a Mysterious Technique of his own that could aid him even in higher realms. Naturally, he could also progress faster in it because it was his creation.
