Major hint
The battle raged in full force as Lex and the other immortals tried to kill each other, right above the floating sea of lava. From afar, those immortals who were watching the fight, full of fear and apprehension, were surprised to see the flow of battle was not what was expected.
Perhaps in lower realms, a person fighting against multiple opponents in the same realm was not inconceivable, yet the immortal realms were not the same just due to how diverse the applications of laws were.
Everyone usually honed a few laws, forming them into extremely potent techniques to deal with various situations. When multiple immortals fought together, even if all of them were bad manipulating laws, their sheer number would make it difficult for a lone immortal to fight against them.