From the very beginning of the trial, it can be said that Musk had gained a lot and even managed to use his strong will in almost every stage. It was useful, but at this stage, it seemed that some force was actually suppressing his will the further he walked and his Primordial spirit was left to withstand the pressure.
Something that he was unaware about the Primordial spirit, not recorded in the Immortal Faction library, was that after the primordial spirit become strong enough, it would transform but the form taken by the cloud like primordial spirit depends on the techniques used to practice it.
Most people strengthen it, and that is the most basic outcome for those in this plane, but transformation was different as it allowed one to be capable of leveraging the power of the Primordial spirit more clearly.