Ren Qing had actually read the records of the two techniques before; throughout the history of the Restraint Officers' Hall, there had never been an eerie-mutation branch related to extending lifespan.
He felt slightly regretful about this, but extending lifespan itself was as hard as ascending to the heavens.
Ren Qing had come into contact with hundreds of techniques; those that truly involved lifespan were extremely few, and all of them carried restrictions.
He understood this well, but since the Ghost Shadow could be carried into the Longevity Forbidden Zone, eerie-mutation branches could also increase his life-preserving methods.
Ren Qing already had three hundred years of lifespan; that was more than enough for the eerie-mutation branches of the two techniques.
However, he could clearly feel that each time his lifespan crossed another hundred-year threshold, the longevity-extending efficiency of the Dream Market decreased slightly.
He forcibly suppressed the stray thoughts in his mind, then focused on the aberration tree of the Human Skin Book.
The aberration tree manifested in the shape of a human hand, its branches covered in tender buds of various sizes.
He had mastered the Human Skin Book for several years, but after advancing to the Ghost Envoy realm, he had never considered eerie mutation, and in daily life rarely cultivated it deliberately.
Ren Qing rested with his eyes closed for a moment, then touched the tender buds with his consciousness; when the information of the eerie-mutation branches entered his mind, the Supernatural Remnant stirred.
All the skin on his body became active, then began to writhe like liquid.
This showed that the Scapegoat Skin had accumulated to the extreme at the Ghost Envoy realm; even though he had not yet consumed lifespan, the Supernatural Remnant was attempting to advance on its own.
If he did not choose a suitable eerie-mutation branch before the advancement, the Scapegoat Skin would complete a mutation at random.
Fortunately, Ren Qing was already prepared.
The Supernatural Remnant of the Ice Crystal Technique, "Stored-Thought Spirit Crystal," was released from the Eternal Prison Manacle.
A crystal shining with seven-colored light formed atop Ren Qing's head; it should have transformed him into a crystalline giant, but did not further aberrate.
What he wanted was precisely the absolutely calm thinking state of the Stored-Thought Spirit Crystal, so he could rapidly scan all the eerie-mutation branch routes.
All kinds of eerie-mutation branches became ten lines at a glance.
His crystallized brain seemed like a supercomputer, mechanically processing information.
The Ice Crystal Technique was even more terrifying than expected.
Ren Qing needed only half a minute to finish scanning all the eerie-mutation branches, even taking time to make simple categorizations of the abilities.
Most eerie-mutation branches focused on strengthening the skin, such as [Ox Hide], [Fleshless], [Eerie Skin], and so on.
[Ox Hide]: causes the Scapegoat Skin to become extremely tough, easily withstanding blades, and able to rapidly recover.
[Fleshless]: the skin gradually thickens, begins devouring one's own flesh and internal organs.
[Eerie Skin]: the human skin becomes completely independent from the body and can temporarily detach and adhere to another creature's body surface.
There were also branches that enhanced substitution-death abilities, like [Shedding Skin] and [Stitching].
[Shedding Skin]: every hundred days the skin molts; during that period one is relatively weak, but the shed skin can block a fatal injury in one's stead.
[Stitching]: can sew another's skin onto oneself, allowing remote transfer of injuries, but causes the skin to rot.
Unfortunately, there was no ability related to extending lifespan.
However, Ren Qing felt no negative emotion; the Stored-Thought Spirit Crystal made him choose an eerie-mutation branch instinctively.
The first eerie-mutation branch was called [Imitative Skin].
[Imitative Skin]: the skin can resist the erosion of alien qi and gradually develop resistance.
By his understanding, the Human Skin Book was a technique that allowed cultivators to adapt to all kinds of harsh environments; Imitative Skin enhanced this trait.
It indirectly boosted the potential of the Scapegoat Skin.
For the next eerie-mutation branch, Ren Qing chose just as decisively, normally, he would have hesitated for a long time.
[Living Skin]: excess fat and essence are stored within the skin and can at any time replenish the body's deficits.
Ren Qing narrowed his eyes; the three eerie mutations of the Scapegoat Skin were thus completed.
[Feeding Skin]: the pores of the skin can replace the mouth in breathing and absorbing nutrients.
Feeding Skin allowed the skin to replace part of the function of the internal organs; combined with Living Skin, one's vitality became as stubborn as a cockroach's.
If the Human Skin Book could apply to the split-soul's body, it could reduce the internal-organ-failure symptoms caused by disease, thereby reducing the rate of lifespan consumption.
The Stored-Thought Spirit Crystal was sealed back into the Eternal Prison Manacle.
A stabbing pain arose all over Ren Qing's skin; then his pores opened, and suddenly he felt a peculiar sense of enlightenment.
He quickly poured Peach Wine over his body.
Once the wine touched his skin, it was absorbed completely.
Ren Qing checked his lifespan; indeed, there was a very faint increase.
He showed joy at once; the split-soul's body would inevitably wither due to the disease type, but if he could use skin to absorb Peach Wine for longevity, the trouble would naturally be much less.
However, since the split-soul's body was generated by the Longevity Forbidden Zone, Ren Qing was not sure whether he could interfere with it, but it was at least an idea.
After the Human Skin Book completed three eerie mutations of the Scapegoat Skin, the information regarding the Yin Runner realm also appeared within the aberration tree.
The Yin Runner realm was called "Ghost God Beneath the Skin."
Ghost God Beneath the Skin meant that the cultivator's skin would strengthen at every moment; it was practically top-grade material for refining Demonic Embryo Artifacts.
Ren Qing rested half a day, then directed his gaze toward the Bone Armor Technique.
Since even the Human Skin Book could not extend lifespan, the Bone-Clad Spinal Apparatus had even less hope.
However, Ren Qing maintained the thought that something might have been overlooked, and using the cold rationality granted by the Stored-Thought Spirit Crystal, he quickly scanned the aberration tree of the Bone-Clad Spinal Apparatus.
But the result was somewhat unexpected.
From roots to branches, the tender buds of the Bone-Clad Spinal Apparatus' aberration tree all appeared quite ordinary, linked to the life-bound artifact.
For example:
[Spine-Link]: connects the Dragon-Snake Spine to a creature's spine, allowing one to forcibly control the body's movements through the life-bound artifact.
Or:
[Regeneration]: when the spine within the body is damaged, it can rapidly recover.
But Ren Qing noticed that a newly grown tender bud atop the aberration tree was different, it displayed a murky dark coloration.
He initially thought this was a special eerie-mutation branch produced because primary and secondary techniques had linked, causing the Ghost Shadow to indirectly affect the Bone Armor Technique.
But unexpectedly, this eerie-mutation branch was intimately connected to the Nether Sea Breathing Art.
Since the Immortal Bone, the spiritual root of the Nether Sea Breathing Art, had fused into the spine, the Bone Armor Technique's essence had changed, tainted with the characteristics of a heavenly-dao technique.
Thus its eerie-mutation branches changed.
[Insect Bone]: the bones' augmentation of strength is greatly enhanced.
[Insect Carapace]: the bones transform into an external bone armor and sprout insect wings.
[Compound Eyes]: the eyes transform into compound eyes..
Ren Qing had no interest in insect-type aberrations; even if they seemed useful, they still headed in the direction of the Heavenly Dao Worm, who knew what drawbacks that might hold.
But hidden within them was an eerie-mutation branch related to extending the lifespan of the split-soul.
[Insect Root]: one's spiritual root transforms into a regenerable organ; a portion separates as the insect root, and the spiritual root can forcibly control the insect root.
Ren Qing chose "Insect Root" without hesitation.
For him, the insect root was the opportunity for longevity, because an insect root was equivalent to the aptitude for cultivating the Heavenly Insect Art.
If Ren Qing's split-soul could cultivate the Heavenly Insect Art, each advancement could increase lifespan, from dozens to hundreds of years.
The only troublesome part was Nether Yuan.
He could only refine an artifact capable of storing Nether Yuan, then have the Ghost Shadow carry it into the forbidden zone.
Once the split-soul became strong enough, it could communicate with the Eternal Prison Manacle within the Longevity Forbidden Zone, enabling a constant supply of Nether Yuan.
[Select eerie-mutation branch "Insect Root"?]
Ren Qing immediately began the metamorphosis of the insect root; his spine developed subtle differences, like a heart that occasionally pulsed.
He then activated "Insect Root"; at once, a violent tearing sensation burst from his spine.
Ren Qing couldn't help but tremble all over, as though his spine were being drawn out of him alive; even the Supernatural Remnant stirred restlessly.
If not for the Ghost Shadow's suppression, the Bone-Clad Spinal Apparatus would likely have rioted.
After more than half an hour, the insect root finished gestating; his spine had shrunk by a large margin, appearing feeble and languid.
The insect root looked no different from an ordinary spine.
The moment Ren Qing brought the insect root into the outside world, it actively absorbed the true yuan in the air, more than enough to refine into a Demonic Embryo Artifact.
But he had been tormented severely; his weakened spine made his entire body limp.
Ren Qing consumed fifty years of lifespan to complete the second eerie mutation, [Regeneration], and only then felt slightly better.
Under Regeneration's influence, his spine absorbed the Nether Yuan within his body, its aura visibly recovering.
Ren Qing tried storing the insect root within the Ghost Shadow, but something unexpected occurred, the two began to fuse.
The insect root seemed to become a pseudo-spiritual-root of the Ghost Shadow.
The Heavenly Dao Worm secreted dark liquid to nourish the insect root, enabling further regeneration and change.
The insect root took on signs of ghost-shadow transformation, though it still needed time to mature.
As for the third eerie mutation, inspired by the insect root, Ren Qing chose a branch that complemented it, [Insect Body].
[Insect Body]: the body hosting the insect root will gradually aberrate into an insect body, becoming more compatible with true-yuan, and gaining improved aptitude.
After the Bone-Clad Spinal Apparatus advanced to the Yin Runner realm, it was called "Immortal Within the Bone"; the Restraint Officers' Hall had no records of it, and its abilities were unknown.
Ren Qing could not discern the Insect Body's effects; he ate some food, sat in meditation, and waited for the split-soul to gestate and his spine to fully recover.
He originally thought gestating the split-soul would take longer, but the insect root needed only a dozen days to transform into a half-illusory, half-solid ghost-shadow insect root.
A faint light flickered between Ren Qing's brows, the split-soul was about to be reborn; it would not be long before he could return to the Longevity Forbidden Zone.
He had just intended to take out the insect root for inspection.
But unexpectedly, due to technique interconnection, the Shadow Ghost Technique inherited part of the "Insect Body" ability.
Yet its manifestation was slightly different.
The insect root detached from the Ghost Shadow not in the form of a spine, but as a half-meter-long black insect, then merged back into the Ghost Shadow.
Ren Qing discovered the black insect was the same type produced by Han Li and the others when cultivating the Heavenly Insect Art, possessing a degree of growth potential.
He could directly bestow the insect root upon mortals, granting them the aptitude to cultivate the Heavenly Insect Art.
Most importantly, the black insects did not take up the Ghost Shadow's volume and could be produced without limit, even summoned in great numbers to attack.
The black insects could improve the split-soul's body; Ren Qing was confident he could extend its life by several years.
Of course, the split-soul did not need to live too long, after all, the Longevity Forbidden Zone was for acquiring temporary lifespan. As long as he periodically gestated a split-soul, it was equivalent to gaining another channel for longevity.
Once everything entered a stable rhythm, Ren Qing would not even need to pay much attention to the Longevity Forbidden Zone.
He could throw a split-soul inside, ignore whatever happened within, and aside from longevity, perhaps even gain additional harvests.
For example: "the Longevity Method"?