Coal Ball is a stray black dog on the brink of death, with a broken leg, festering skin, and an eye full of hatred. Lu Chen contracts it and feeds it industrial sulfuric acid, triggering its transformation into a Bio‑Demon Dog. It gains black chitinous armor, corrosive blood, and the ability to spit strong acid. It is fiercely loyal to Lu Chen, shows a brutal and fearless nature, and quickly evolves further. Its first stage grants it skills like Acidic Spit and Corrosive Blood.
