Reili
So one of the reasons for Rokarn's apparent difficulty in being defeated seems to be his "ability" to actively copy his opponent's powers/abilities/traits(physique?) at a slightly weaker level, such as copying Makron's Demon God Physique, or the "Fallen Energy/Trait Corrosion" like Syradil the Dragon Empress did in her "Psuedo-Fallen" state. Yeah, basically an active/sudden spike in difficulty mid-battle if it drags on long enough via a copy-cat "gimmick", irritating to say the least.