External Soul Bone

Biodata

Feature	Value
Name	External Soul Bone (外附魂骨)
Alias(es)	Heavenly Thunder Six Orifices External Attached Soul Bone; Six Heavenly Thunder Bones
Type	External Attached Soul Bone
Owner	Mu Yuan
Status	Fused with Mu Yuan; forms the original structural foundation of his Eight-Armed Demonic God path
First Appearance	9

Power Progression

Stage / Realm / Level	Chapter	Notes
Condensation and fusion	9	Condenses during Mu Yuan's absorption of the Deep Sea Demon Octopus Soul Ring by gathering Soul Power dissipating from the beast's corpse.
Six-arm manifestation	9	Attached to Mu Yuan's back and integrated with his arm bones, scapulae, and ribs; condenses six additional arms from Heavenly Thunder Power and Vajra Power. Together with his natural arms, it creates an eight-armed form.
Eight-aperture structure	151	Revealed to be an eight-aperture bone: two apertures connect to Mu Yuan's original arms, while six correspond to the additional arms.
Nourishment through torso bone	151	Benefits from Mu Yuan's fusion with the Hundred-Thousand-Year Eight-Petal Immortal Orchid torso bone, becoming capable of bearing the pressure of multiple hundred-thousand-year soul bones and returning nourishment to his body.
Arm-bone integration path validated	152	Mu Yuan's successful fusion of a Radiant Right Arm Bone confirms the feasibility of equipping the Eight-Armed Demonic God with soul bones across its arm positions.
Four-arm soul-bone placement test	150 151	During the Radiant Right Arm Bone fusion, Mu Yuan identifies the original right arm and a right arm shaped in his special state as distinct arm positions. The Six Heavenly Thunder Bones manifest as an octagonal-wheel-like pattern while he selects another right-arm position for fusion.
Eight-arm high-grade manifestation	184	Mu Yuan manifests all eight arms in battle. The final two arms are nearly solid, while the complete configuration displays paired thunder, mountain-and-river, fire, ice, light, and darkness attributes.
Darkness-arm integration	263	The Heaven-Defying Demon Dragon Emperor's Left Arm Bone merges into the darkness-aspect arm of Mu Yuan's light-and-dark dual form, further realizing the multi-arm soul-bone configuration.
Eight-Armed Demonic God Martial Soul evolution	274 277	Mu Yuan reorganizes the Eight-Armed Demonic God Images and expands the former Arm Martial Soul into the complete Eight-Armed Demonic God Martial Soul. The External Soul Bone's eight-arm framework is surpassed by a true evolved Martial Soul supported by Blood Essence, high-level soul bones, and the completed arm configuration.
Thunderfire phase refinement	314	The Heavenly Thunder and Fire Phase arms draw in thunderfire power while refining compatible Demon God Pillars; Soul Bone radiance blooms from within both arms.

Background / History

The bone originated from a Deep Sea Demon Octopus killed by Mu Yuan while Du Busi restrained it. Rather than appearing as a conventional drop from the corpse, it condensed as Mu Yuan absorbed the octopus's Soul Ring and unconsciously gathered the Soul Power that dispersed after its death. A hexagonal-compass-like pattern first formed at his scapulae before the bone emerged in his Mental World. 9

Its formation was shaped by Mu Yuan's internal powers. Vajra Power and Heavenly Thunder Power converged on his back, where the bone broke through and manifested six additional arms. Du Busi recognized it as an External Attached Soul Bone, a treasure rarer than even the soul bones possessed by contemporary powerhouses. 9

The bone later became central to Mu Yuan's plan to construct the Eight-Armed Demonic God. Its six extra arm positions could potentially be fitted with soul bones through soul-tool Core Array technology, while its eight apertures ultimately aligned with all eight arms of his visualization. 65 151

During Mu Yuan's attempt to fuse the Radiant Right Arm Bone, the Six Heavenly Thunder Bones manifested behind him as an octagonal-wheel-like pattern. This process clarified that the bone's eight apertures could correspond to different arm positions, although the arms not yet shaped through his special state lacked a sufficient foundation for immediate soul-bone fusion. 150 151

As Mu Yuan successively established more complete arm positions, fused high-level arm bones, and reorganized his Eight-Armed Demonic God Images, the original external-bone framework developed into the basis of a genuine Eight-Armed Demonic God Martial Soul rather than remaining solely a visualization construct. 184 263 274 277

Appearance

When manifested, the External Soul Bone is anchored across Mu Yuan's back and appears as a six-aperture structure behind him.

• Initially forms as a hexagonal compass-like pattern at the scapulae. 9
• Connects to Mu Yuan's arm bones, scapulae, and ribs as though naturally integrated with his skeleton. 9
• Contains eight apertures: two for Mu Yuan's natural arms and six for the extra arms. 151
• The six apertures outline and align with the six additional arms of Mu Yuan's Eight-Armed Demonic God visualization. 151
• During the Radiant Right Arm Bone fusion, it manifests as a pattern resembling an octagonal wheel behind Mu Yuan. 151
• As Mu Yuan's configuration matures, all eight arms can manifest with tangible form and paired elemental attributes; the final two arms are initially almost solid rather than fully corporeal. 184
• Following Mu Yuan's Martial Soul evolution, the Eight-Armed Demonic God can manifest as his actual Martial Soul instead of merely a Visualization Method construct. 277

Abilities & Functions

Six Additional Arms

The bone condenses six arms from Heavenly Thunder Power and Vajra Power, increasing Mu Yuan's effective arm count from two to eight. 9

• Establishes the physical basis for the Eight-Armed Demonic God. 7 9
• Expands the portion of Mu Yuan's body associated with his Arm Martial Soul beyond his original limbs. 9
• Gives his back and potentially his entire torso a path toward becoming part of his Body Martial Soul. 9
• Provides six supplementary positions that correspond to the extra arms of Mu Yuan's Eight-Armed Demonic God visualization. 151
• Supports the eventual manifestation of a complete eight-arm configuration, whose arms carry opposing elemental pairs. 184

Heavenly Thunder Integration

The bone uses Heavenly Thunder Power as part of its structure and development.

• Its six added arms are condensed through Heavenly Thunder Power combined with Vajra Power. 9
• It is alternatively identified as the Six Heavenly Thunder Bones. 151
• Mu Yuan's adaptation to Heavenly Thunder Power supports the later fusion of a compatible Yin Thunder Hundred-Thousand-Year Right Arm Bone. 100
• The Heavenly Thunder Phase later refines thunderfire power through its corresponding arm position, with Soul Bone radiance manifesting within the arm. 314

Soul Bone Compatibility and Nourishment

The External Soul Bone serves as a framework for Mu Yuan's future multi-bone arm configuration.

• Mu Yuan seeks Core Array technology capable of integrating soul-bone power into Soul Tools, intending to apply it to the bone's six extra arms. 65
• The Hundred-Thousand-Year Eight-Petal Immortal Orchid torso bone possesses a passive ability that continually interacts with Mu Yuan's Eight-Arm Node, allowing future harmonization with arm bones. 90
• After being nourished by the Eight-Petal Immortal Orchid, the bone can endure the pressure of multiple hundred-thousand-year soul bones and use them to nourish Mu Yuan's body in return. 151
• The Six Heavenly Thunder Bones act as a buffer that reduces the pressure borne by Mu Yuan's Eight-Petal Immortal Orchid torso bone. 151
• Mu Yuan's fusion of a Radiant Right Arm Bone into a separately shaped right-arm position confirms that soul bones can be assigned beyond his original limbs. 150 151
• The Heaven-Defying Demon Dragon Emperor's God-level Left Arm Bone later integrates into Mu Yuan's darkness-aspect arm. 263
• Its development supports Mu Yuan's goal of fusing eight arm soul bones, six more than a conventional Soul Master could possess. 152

Structural Role in Martial Soul Evolution

The External Soul Bone's greatest function is its role in changing the conceptual Eight-Armed Demonic God into a viable cultivation structure.

• Its eight apertures provide the correspondence between Mu Yuan's original arms and his six additional arm positions. 151
• The bone allows Mu Yuan to distinguish and assign soul-bone positions among the arms he has shaped through his special cultivation states. 150 151
• The increasingly complete arm configuration, combined with Blood Essence cultivation and numerous high-level soul bones, enables Mu Yuan to evolve his Arm Martial Soul into the Eight-Armed Demonic God Martial Soul. 274 277
• Even after this evolution, the external bone remains the original six-arm structural foundation from which Mu Yuan's eight-arm path developed. 9 151

Story Role / Major Arcs

Deep Sea Demon Octopus Hunt

Du Busi deliberately prolonged the octopus's suffering after sensing that its intense hatred and desperation might increase the chance of a soul bone forming. Mu Yuan killed the restrained Soul Beast with a strike guided by Demonic Qi and Blood Qi, then obtained the External Soul Bone during Soul Ring absorption. 9

Eight-Armed Demonic God Development

The bone transformed Mu Yuan's Arm Martial Soul path by providing six supplementary arm positions. Its existence made the Eight-Armed Demonic God more than a conceptual cultivation direction and enabled later plans for an eight-arm soul-bone configuration. 9 65 151

Hundred-Thousand-Year Soul Bone Integration

After Mu Yuan received the Eight-Petal Immortal Orchid's Hundred-Thousand-Year torso bone, the torso bone's passive function began harmonizing with the Eight-Arm Node. This later nourished the External Soul Bone and strengthened its ability to support additional high-level soul bones. 90 151

Eight-Arm Eight-Image Development

The bone's aperture framework becomes directly relevant when Mu Yuan attempts to place the Radiant Right Arm Bone into one of his separately shaped right-arm positions. This confirms that the Eight-Armed Demonic God path can accommodate arm bones beyond the ordinary two-arm limit, although not every position is initially sufficiently developed for fusion. 150 151

Mu Yuan later manifests all eight arms in combat, including arms carrying heavenly thunder, fire, ice, light, and darkness. The Heaven-Defying Demon Dragon Emperor's Left Arm Bone then fuses into the darkness-aspect arm, advancing the configuration toward a true multi-arm soul-bone system. 184 263

Martial Soul Pioneering

After reorganizing the Eight-Armed Demonic God Images into a more complete structure and condensing his final Blood Essence Soul Rings, Mu Yuan expands the scope of his original Arm Martial Soul. The Eight-Armed Demonic God subsequently appears as his evolved Martial Soul rather than merely a Dharma Image generated by visualization. 274 277

Trivia

• External Attached Soul Bones are described as so rare that even Du Busi, Mu En, and Long Xiaoyao—each possessing multiple hundred-thousand-year soul rings and soul bones—do not possess one. 9
• The bone's greatest value to Mu Yuan is not immediate combat performance, but its role in advancing the Eight-Armed Demonic God cultivation path. 151
• Although it is commonly called the Six Heavenly Thunder Bones because it outlines six extra arms, its true structure contains eight apertures when Mu Yuan's original pair of arms is included. 151