Having obtained the jade slip recording the "Basic Purification Technique," the atmosphere in the stone chamber was both elated and tinged with a sense of relaxation after completing the task. The ancient jade slip had been stored away by Xiao Qi, leaving the stone platform empty; this cave abode left behind by predecessors seemed to have been fully explored.
"It seems the opportunity here has been obtained by Junior Brother Xiao Qi. We..." Before Liu Yun could finish, Mu Qingfeng, who had remained silent and was still sharply scanning every corner of the stone chamber, suddenly raised his hand to stop her.
"Wait." Mu Qingfeng's voice carried a rare gravity.
Everyone immediately fell silent, following his gaze. They saw Mu Qingfeng staring at a dark corner deep within the stone chamber. The light was dimmest there, where the rock wall met the ground, piled with some fallen rubble from cracks above and accumulated dust from years, appearing no different from other corners of the chamber.
"Eldest Senior Brother, is something wrong?" Shi Jian asked gruffly, clenching his fist.
Mu Qingfeng did not answer but slowly walked toward that corner. He crouched down, extended his right index finger, with a strand of extremely pure and gentle cyan spiritual power swirling at his fingertip, carefully brushing away the surface dust.
As the dust was brushed away, the slightly darker rock surface beneath was revealed. Mu Qingfeng's fingertip lingered at a spot where the rock surface seemed to have an extremely faint, light gray stain, as if slightly stained by ink, almost blending with the rock's own texture—impossible to detect without his powerful spiritual sense and keen observation.
The cyan spiritual power at his fingertip lightly touched that light gray stain.
"Sizzle..."
An extremely faint sound, like cold water dripping into hot oil, was heard. The strand of pure cyan spiritual power at Mu Qingfeng's fingertip actually wavered slightly, as if encountering its nemesis, with even a tiny sign of erosion and dissolution at its edge! Meanwhile, that light gray stain seemed to be activated, emitting an indescribable, chilling aura—cold, dead, and full of corrosive intent!
This aura was extremely thin, so weak it was almost negligible, yet its nature was terrifyingly high, far surpassing any energy level they had ever encountered! Merely sensing this trace of residual aura made Liu Yun, Shi Jian, and Xiao Qi simultaneously feel a chill rise from their hearts, and the circulation of spiritual power within their bodies became slightly sluggish.
"This is... demonic energy?!" Liu Yun exclaimed in a low voice, her face suddenly changing. As a sword cultivator, she was particularly sensitive to such sinister auras.
Shi Jian also drew a sharp breath, his bell-like eyes widening: "So... so pure demonic energy! It's countless times stronger than what we encountered on those demonic cultivators we exterminated before!"
Xiao Qi's heart shook even more violently! This cold, dead aura with extreme corrosive intent was so similar to the demonic cultivator's aura he felt on the night Xu Lan Mountain Manor was destroyed in his memory! Though infinitely weaker, the evil and terror originating from its source were exactly the same!
Mu Qingfeng slowly withdrew his finger, his expression as grave as water. The strand of spiritual power at his fingertip had already dissipated, and that light gray stain returned to silence, as if everything just now was an illusion.
"No mistake." Mu Qingfeng spoke solemnly, his tone unprecedentedly serious. "It's demonic energy residue. Moreover, it's of extremely high quality and purity, definitely not something ordinary demonic cultivators could possess. The being that left this trace, its cultivation level... is probably far beyond our imagination."
He stood up, sweeping his gaze over the doubtful and alarmed group, continuing his analysis: "This demonic energy residue is already extremely faint, almost assimilated with the rock. If not for the passage of time causing most of it to dissipate naturally, then it was deliberately purified by some force. But judging from the residual nature, the demonic entity that left this trace back then, its power was probably... at least at the Golden Core stage, or even higher."
A Golden Core stage demonic entity?! Hearing this, everyone's hearts sank. The Golden Core stage, for Qi Condensation stage disciples like them, was like an insurmountable mountain!
"This... this secret realm, could it be sealing some ancient demonic entity?" Shi Jian's voice became somewhat dry.
Liu Yun forced herself to calm down, analyzing: "Judging by the state of this trace, it should have been a long time ago. The owner of this demonic energy might have already left, or perhaps... has perished. Otherwise, with its cultivation level, the moment we entered the cave, we would have probably..."
She didn't finish her words, but everyone understood the implication. If that demonic entity were still here, they would have no chance of survival.
Mu Qingfeng nodded: "Liu Yun's analysis is reasonable. This trace is from ancient times; the demonic entity's main body is most likely not here anymore. But this matter is still of great significance."
He looked toward that corner, his gaze profound: "This stone chamber might not be simply a place of inheritance. Could there be a connection between the senior who left the 'Basic Purification Technique' and this trace of demonic energy residue? Did the senior suppress a demonic entity here? Or... did the demonic entity stay here, or even engage in battle with the senior?"
Various speculations arose in everyone's minds, casting a strange and heavy veil over this originally seemingly ordinary stone chamber.
Xiao Qi subconsciously touched the jade pendant on his chest. The pendant remained warm and smooth, but when sensing that trace of demonic energy residue, he seemed to detect an extremely faint tremor within the pendant's pure energy, as if encountering a natural enemy.
"Basic Purification Technique"... purification... demonic energy...
Could it be that the purpose of the master who left this technique was to deal with such high-level demonic energy? What connection does this have with his family?
"We must remember this matter; after leaving the secret realm, we must immediately report to the Sect Master and Elders," Mu Qingfeng decided. "This place is not suitable to stay; we have completed our exploration and must leave immediately."
No one objected. The discovery of this trace of demonic energy residue weighed like a massive stone on everyone's hearts. The joy originally brought by obtaining the inheritance was now diluted by the shadow of this potential, enormous danger.
They took one last look at this empty and eerie stone chamber, and the nearly imperceptible light gray stain in the corner, then turned without hesitation and quickly, cautiously retreated from the cave along the path they came.
Seeing the slightly glaring sunlight and fresh air outside again, everyone felt as if they had been in another world. The cave entrance behind them remained concealed by vines, as if nothing had happened.
But everyone knew that this discovery was probably far more serious than an incomplete auxiliary cultivation method.