Mountain Spider had asked to fight Peter primarily because Peter himself was far too extraordinary. If he was going to take part in the Immortal Trial, Mountain Spider needed to get a rough measure of his strength. Only then could he determine how much power to use during the trial.
After all, if he used the same trial difficulty as he had for previous Immortal Weapons, Peter would probably clear it in a matter of minutes.
Meanwhile, Peter changed into a clean outfit that allowed him to move easily. This battle was different from his fights against supervillains. To better adapt to and understand Mountain Spider's Immortal Energy, he had been forbidden from using any powers not granted to him by the Spider Totem. In other words, his nanotech suit, magic, Anti-Venom, and the like were all off-limits.
That was also one of the trial's requirements. Technology was considered unclean, and those powers could not be used in the trial. As for Silk, since he could not produce it himself, he might as well pretend it did not exist. The Web Shooter was forbidden too. They gave him a bundle of rope and told him to use it as webbing.
So Peter arrived at the vast field of stone pillars outside the city with a bundle of hemp rope slung over his back, each strand as thick as the Silk fired by those middle-aged women in their forties. Above was a massive web, and below were sharp stone spikes. The two took their stances, both ready to fight.
Daniel watched from the side. He had fought Shou Lao many times, and the most dangerous of them all had been during the Immortal Trial. The Immortal Beasts would mercilessly kill any unqualified trial-taker. Peter did not have that problem, but his