Although it did not seem like it, as Lex walked quietly with the group towards the Chamber of Secrets, he was actually doing multiple things at the same time. A part of him was paying attention to the ongoing lightning tribulation. The devil… to be entirely honest, he had started the tribulation with a convincing performance, but the longer it went on, the worse his condition became. Parts of his body were already charred and smoking, and he had given up his humanoid form to revert to his true devil form.
Lex expected that the form would be quite gruesome, but it was far from the truth. While the large body with wings and horns and red skin looked mighty intimidating, it also looked regal and authoritative - not at all the vile, disgusting appearance Lex had been expecting.
But whatever the case, if there was to be a fire tribulation following the lightning one, he did not know how the devil planned on surviving with its existing wounds.