Right after Lux superimposed his domains, or at least tried to, the backlash of failing caught up with him and he was left covered with blood on the ground, his clothes torn apart due to the lacerations that appeared on his skin.
His calm eyes meant that the wounds weren't as serious as they looked to be, or maybe he was simply immune to a little bit of pain after suffering so many times before when trying to get both domains to work at the same time.
He could deploy them separately, and in different zones, but never in the same place or at the same time.
His True Light World was a calm Domain with a lot of uses, but his second Domain, Chaos World, was another story.
It was an explosive Domain that focused on attacking his enemies, forgetting any kind of defensive measure.