Shi Lei used his Innate Perception to discover a strange space within the Black Stone Fortress. However, this space was blocked by the stone walls of the fortress.
These stone walls clearly served to block cultivators' Divine Sense; the Divine Sense of ordinary cultivators was unable to penetrate the stone walls to perceive the existence of this space.
At this moment, the cultivators inside the Black Stone Fortress were continuously slaughtering the Yin Ghosts and Monsters within the Ghost Cave.
Chapter 406