C708
The Immortal Execution Demon Cave was a forbidden area for Myriad Great Immortal Domain, and it was also an excellent place to level up cultivation. It was likely that no one in the entire Immortal Realm would be able to find a second place to do so!
For example, Myriad Great Taoist Immortal, the powerful Immortal Emperor. He could only stay inside for around 30 years each time