The fact that the Temple Alliance could obtain intelligence regarding the Demon Hunter Slayer indicates that human spies have successfully infiltrated the core of the demon race. However, identifying them is not particularly difficult. After all, the Demon Gods would never leak secrets, and any suspicious activity would most likely stem from A Bao’s circle.
Bai Yue specifically sought out A Bao, urging him to keep a close eye on the demons around him—especially the servers and attendants within the palace, as they were the most likely candidates for humans using serum to disguise themselves.
Over the past six months, the demons’ apothecaries had perfected the concoction of this "demon serum." It is a blood-based agent extracted from high-ranking demons; one adult demon’s total blood volume can produce three doses. The efficacy of the serum increases with the donor's power level. For instance, an Eighth Tier demon provides enough blood for ten doses, with effects lasting up to three months. If the blood is sourced from the top three clans—the Heaven-Defying Demon Dragon Clan, the Moon Demon Clan, or the Star Demon Clan—it can even permanently enhance external spiritual power.
Chapter 66