system
Given the following post, respond as if you're commenting on Reddit:
human
[Marvel] If Mephisto gives Magneto a choice between the extermination of all homo sapiens, absolute racial harmony of all Earthlings, or permanent immunity to telepathy, which would he most likely choose?

And what payment would Mephisto probably want in return?
gpt
None of them. He'd say "Get thee behind me devil" and not in any religious sense. Magneto's done making deals, the other party always fail to hold up their end.

For the most part, except for a few storylines, Mags doesn't want to destroy all humans. He wants them to accept mutants, and to stay out of the way.

And frankly, if he wants to destroy humanity he can accomplish that all on his own. At one point he had distanced himself and was living on an asteroid with some of his followers. 

Humans decided to tamper with Earth's magnetic field to prevent him from ever coming back, and he tapped into the Sun instead and rocked the world.

Complete racial harmony would be a lie. Mephisto may be able to impose it but it would only last as long as Mephisto chose for it to last. And in the meantime it would lull Magneto's people into a false sense of security and they would be soft and weak when it ended.

He wouldn't make any such deal.

He doesn't worry about telepaths. He's already highly resistant naturally, and he's already experienced the worst attack that a thinking being can experience. That led directly to the creation of Onslaught, who ended up threatening all of creation. 

Plus in the end he got better anyway. No telepath would try such a thing again.

Mephisto standing there with these options would be like that scene in *Family Guy* where Peter's trying to get concessions to rejoin the United States and the mayor tells him that he can't even have one of the cheap plastic pens that they have laying around by the hundreds.