Heaven's Stealer Dismantler Manual {First Vol} (1)

Nevertheless, Ace was determined to learn this soul path technique because if he could just achieve a low stage level of the first realm he can simply order someone who was under his control to commit suicide, and they'll do it with no hint of hesitation or resistance! 

The most magical and dreadful thing about this technique was the victim won't even feel or remembered that he was assailed, or controlled with this technique!

This simply means Ace can control a person and asked him about the location of the treasury or anything he wanted without wasting time using soul probing, and that person would not only tell him everything, but he'll even forget about it the very next moment! 

Besides, this technique can work on far more powerful opponents if he had high-level mastery over laws inscribed in this technique manual.