Diablo's Terrifying Potential: Analyzing the Primordial Black in Tensura 

Diablo is Rimurus subordinate strongest even in Ln 21. Guy already had his name when he fought Veldanava and was already a true demon lord at that time. Spoilers: Diablo is so op that he can manipulate things like gifts that come from evolution and even his own evolution. He fought Zelanus in an 1v1 in base and still had the upper hand. He defeated Ultimate skill user with only his unique skill no dif. Things like Ep, magic, skills and common logic is nothing in front of diablo. current Diablo is at Guys level or even above. even Ln 14/15 Diablo could defeat Velgrynd. Not to mention his skill that makes him nigh omnipotent

I think im the most powerful last time i checked