I bring this up because this episode (and the related What-If that was released a few years ago) gives us insight into a villain as he becomes powerful beyond imagination. The first thing Doctor Doom does with his powers is restore his face. He later presents himself to the heroes and claims they have nothing to fight over any longer. If they insist on fighting him, he will defend himself. Captain America claims that Doctor Doom is still to be opposed, citing the fact that the first thing he did was restore his face. It brings the pettiness right to the surface. If Doom is still so interested in such minor things, how noble, how far-looking can he be? (I can't remember if he specifically threatened their lives, though I'm inclined to say he didn't, as I don't recall it being mentioned that much.) It brings that issue of pettiness right to the surface. A hero is expected to have a certain amount of vision, not to focus on small or superficial things.
The heroes hem and haw over what to do, and they eventually call a vote (“It must be unanimous!” Really, Captain America, why is that? Oh, more dramatical? Then carry on.) on whether or not to oppose the omniscient, omnipotent Doom, knowing full well they could be destroyed just for deciding to oppose him. Troubled, Colossus casts the final vote and they're hit with a bolt of lighting from the sky, killing them all (You might call bullshit on Thor and Hulk being killed by lightning, but it's no ordinary lighting; It's lightning from the stolen powers of a guy who called Galactus over to fight ants on his giant melange planet, which Galactus tried to eat because, hey, free sampler platter. Also; this bolt cracked Cap's shield. I don't know how much that happens in the Marvel universe it may very well be a trope at this point, but I've only seen it happen once, and it was well-used.
Super-Doom, if you will, is petty, belligerent, and deadly. You could say reasonable, polite, and effective, but with the exception of giving him politeness points for telling the heroes to fuck off before he has to kill them, he's really just a tyrant, destroying even those who can't threaten him with excessive force just because they want to hurt him. You can easily contrast with Superman who will warn those who cross him and give them benefit of the doubt before engaging in a dramatic escalation of force with them. Superman usually starts small because he doesn't want to hurt his enemies any more than necessary. Doom has no such compunctions.
In the original story, Doom (with trickery by the mostly-depowered Beyonder) imagines a scenario in which the heroes might have survived. Omniscient though he is, he is a weary human wielding the powers of gods, and dares not turn even a fraction of his attention to the heroes, should the energies he expends make his fears reality.
This is a clear case of self-defense.
It's all for naught however (Which make every Marvel comic you’ve read since ’85 a spoiler for Secret Wars. Thanks Marvel, you jerks!). The heroes have survived and regrouped; they rally and give The Beyonder a chance to restore himself and take his massive power from Doom. So he does, and there's an epilogue, etc., etc..