Pralaya operated on a greater scope than Nekron(multiversal compared to universal), but yeah, how can one embodiment of absolute oblivion defeat another..?
Always with these 'next big thing' fly by night no name cosmics, they are defeated in the most idiotic ways by a handful of heroes.
Look at what it took to hand Nekron his losses. The entire EM Spectrum Corps, Guardians of the Universe, summoning the Life Entity, etc... and still he didn't go down. It took severing his tie to Black Hand to finally do it.
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..even the outer hells are indifferent matters for they bow only to potent and archaic Nodens.