I seem to recall a few years back, some huge event in the Marvel Universe, something about some character named Onslaught killing everyone (?). I’m kind of foggy on the details, but apparently the Marvel Universe rebooted after this story arc. I’ve seen some Dopers mention it in passing…nothing in detail. But the little mentioned seems to be not positive. So what was wrong with Onslaught? And what the heck did he do?