The Shadow Phantom Technique is a powerful and sinister martial art that blends the control of the dead with lethal combat techniques. It was developed by Lei Fei to maximize his unique mystical ability, making him a formidable force on the battlefield. This martial technique thrives in a chaotic battlefield filled with restless souls of warriors, the user had a higher chance of losing in a one-on-one battle, than when getting ganged up on.
That explained why Lei Fei fought hundreds of guardians, relying solely on his martial arts, and killed most of them.
The Shadow Phantom martial technique was special because it complimented Lei Fei's spectral conductor inheritance. He could collect and store souls before joining a fight, that way he was always at full strength, but Lucius didn't have such privilege. Regardless, the martial technique was still considered a top-tier demonic art, even without Lei Fei's power.