If one does not have enough confidence in their own foundation, the vast majority of cultivators would not choose to attempt this during a breakthrough.
Because once the "Open Heaven Gate" fails, before the Golden Nature can descend, one's own Inner Core will be shattered by backlash, leading inevitably to death and the dissipating of the Dao.
The reason Shen Wen'an chooses this path is primarily to lure out people from the Underworld.
Last time at Luoxia Mountain, during a brief encounter with someone from the Underworld, he captured a trace of Yin Qi from the other party, which ultimately manifested as a strange mark on his Lifebound Magical Sword.
This mark is incomplete, and this time he wants to try again to see if he can complete it.
Only, now what surprises him somewhat is that after "Sword Opening Celestial Gate," he actually attracted two people from the Underworld.
"Let's give it a try first."
