This mark was a Secret Technique exclusive to the lineage of the Huanyue Sect Leader. Its purpose was to attach to a junior family member. Ordinarily, it would never activate. Only when the junior faced a life-threatening crisis would the events happening around them be transmitted into the caster's sea of consciousness. If the distance was short, the caster could immediately mount a rescue. Even if the rescue failed, they could still discover who was responsible for the junior's death and then mobilize the full strength of the sect to avenge them.
Therefore, as Huan Xinghe's life hung by a thread, everything that happened was transmitted into Huan Yuehua's sea of consciousness.
Initially, Huan Yuehua only saw Huan Xinghe fighting the Mudhead Monsters. Having entered the Chaotic Labyrinth before, he naturally knew how formidable the creatures were and silently cursed his son's carelessness in provoking such terrifying beings.
