Bai Kou had complete control over her spiritual power when she displayed her spiritual world in its entirety before others. Xu Huo guessed that she must have transcended the need for a medium in the form of an artifact, or rather, the artifact's role in the process was minimal.
She had given herself a "Star-binding Sphere," which was a medium for her powers. After his Super Evolution, Xu Huo was unable to transform his spiritual power into a tangible force of attack. Using a medium, he could create a very small manifestation range of his spiritual world. The only two times the range expanded were when he was using the hospital that had become a random copy instance.
He still hadn't mastered how to use his spiritual power to affect others, but the "Murmur Sphere" was also an artifact designed for Psychic Attacks. Perhaps it could offer a breakthrough.