Inside the Yin Tower, wreathed in swirling blue mist, Si Ren and Rulai stayed within a meter of each other; any further apart and they would lose sight of one another.
Their heightened senses were also rendered useless, as the blue mist seemed to carry a powerful interference.
To avoid getting separated, they tied a Soul-Gathering Lock around their waists. This way, as long as the rope remained unbroken, neither of them would get lost in the Yin Tower.
Chapter 644