The Abyssal Secret Realm, one of the many secret realms controlled by the Nine Sacred Mountains, is specifically used to temper one's mental consciousness.

The Abyssal Secret Realm is divided into seven layers. The further one goes, the stronger the tempering effect on the mental consciousness, but the threshold to enter the realm is extremely high.

Just the first layer requires a full ten thousand battle merit points to enter, the second layer requires twenty thousand, and so on.

Su Xin had previously gained a substantial amount of battle merits on the battlefield, so he didn't hesitate to spend ten thousand battle merit points to enter the first layer of the Abyssal Secret Realm.