Mr Shadow is a being of pure evil. He is pretty smart and his defense is enough to stop nuclear missilles with little effort. Still, Galactus has casually destroyed planets and more in the past. Galactus has fought and defeated many powerful enemies with his energy blasts in the past and I think that he can win this round. Galactus wins.
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OK, I can agree with that one. It’s tough to say, but I think Galactus might be able to conjure up an attack similar to the Light of Creation and thus actually damage Mr Shadow
Definitely, as one of the 3 great forces in the marvel universe, he’s got access to many elements and I’m sure that some are light based (The power cosmic could be considered partially light)