To prevent any unexpected situations, Feng Ning embedded three additional Sound-Transmission Stones onto the Spirit-Locking Ring she had crafted. Each stone had a transmission limit of one quarter of an hour and would become useless once depleted.
Feng Ning had warned them to use the stones only at critical moments.
Their transmissions could only reach her; with limited materials, she had only managed to find a single piece of magnetic stone for receiving, and she had no idea if it would be enough!
Chapter 37