Mo Heng serves as Chief Engineer of the Taibai Empire, overseeing the design and production of Construct war machines – powerful wooden and brass automatons – for military use. His expertise lies in mechanical engineering and artifice.

His family name translates to "Ink," his given name meaning "Balance" or "Scale." He hails from the ancient Huaxia Tribe, predating Han Chinese identity.

Driven by horror at the civilian casualties caused by his inventions, Mo Heng defects from the Taibai Empire after his tenure as Chief Engineer. He joins the Resistance led by Xiang Chu. Before defecting, he initiated the design of the Zhengtian, a massive construct superweapon intended to harness Black Fire energy, though its schematics remained incomplete when he departed.

Within the Resistance, Mo Heng focuses his engineering on countering the Empire. His key contribution is the Black Fire Armor, a magical prosthetic amplifier granting enhanced flight and combat abilities. Early versions were unstable, prone to triggering uncontrollable berserker states or severely harming the user's soul.

Mo Heng mentored Pu Zhao, recognizing the enslaved youth's exceptional memory and engineering aptitude in the imperial forges. Mo Heng's defection creates a pivotal conflict for Zhao, who ascends to become the Empire's Chief Engineer. Zhao later utilizes his skills and recollection of Mo Heng's incomplete Zhengtian blueprints to complete the superweapon for the Empire.

Mo Heng's continuation of weapons development for the Resistance, despite leaving the Empire over war's civilian cost, stirs controversy. Critics brand it hypocritical, arguing rebellion inherently inflicts similar violence and collateral damage.