Re: "So, Thor hits Superman with Mjolnir..."
Ok, this whole "vulnerability to magic" thing has gotten completely out of hand. Look, there's one reason and one reason only that he has this so-called vulnerability: Mr. Mxyzptlk
Superman once was bulletproof. Then he was The Man of Steel. Then he was invulnerable. Problem with invulnerability-it's boring. He can't be hurt...so what if we can screw with him a little? Mxyptlk was the villain intended to offer weird challenges without having to throw a punch. If he wants to make Supes into a hedgehog, he can. "But he's invulnerable! He can't be harmed. and changing him into a hedgehog qualifies as harm," the fans point out. "Ah," say the writers, doffing their tap-dancing shoes, "but that invulnerability doesn't work against magic. He's vulnerable to magic." "Oh," note the mollified masses. "Ok, we get it." The writers exhale a sigh of relief, not realizing the monster they've unleashed, and go about exploring new colors for kryptonite.
That's it. End of story. In the old days (you know, before 1996) even mystical foes needed red sun radiation or kryptonite to cause actual harm. ("That viking warrior doesn't know it, but his magic sword has *gasp* red sun radiation!")
There. Now you may continue ranting.