Quote: But he does seem to be on a greater scale and level than Proteus. Is Korvac immune to reality-warping? I guess that I pick Korvac.
Proteus only has a limited form of reality warping - i believe he can only affect a limited area. 100 feet or something - that makes his threat level far more limited than a low level cosmic being like Korvac imho.
I think Proteus area of effect might have increased in Exiles a bit, where he also found a "cure" to his metal weakness; he had better feats there, but it probably helped that those were all alternate disposable realities.
On the other hand, Korvak stole power from Galactus, so he originally wasn't that strong as well before that power up... I think Korvak would win if we consider the top of his power against a standard Proteus; the Exiles one, i would give a fair chance at winning, no more than 50/50