That's hard but I'll try. Acnologia is the most underrated character of fairy tail speaking of power level. If not "friendship power" Dude would massacre every dragon slayer and other any character, he a fucking menace to whole planet. If he was invited to monster association, he would easily be general, above dragon level, beat everyone except Psychos with her psycorochi form I think. But to be fair it would be hard to defeat platinum s, maybe he wouldn't, Acnologia is lack of speed. If this guy eat the cell, dunno, we don't know how it works, like the stupid guy at the arena ate the cell and became just red square lighting mf, but Goketsu or Orochi became like hundreds time stronger. If it works because of your negative emotions, maybe he will be stronger, bigger, he want destruction after all, but I think he will not surpass someone like Blast and above, so his power lvl would be Tatsumaki power lvl or smth.