could he phase through the forcefield? The field is actually a superstrong field that repels mass and energy o the atomic level. Basically, its a force that repels atoms that come in contact with it. If martian manhunter actually phases through metal and stuff, i doubt he has mass. So he could phase through his shield, right?
For god's sake...
Actually, this would be a harder fight for Magneto than the Superman fight. Phasing won't work...Hub tried and failed. Vision was also unable to do it. In fact, there's a chance MM could kill himself in the process...his atoms would essentially be repelled and possibly tossed in a million directions. But I'd have to know more about the science behind his phasing to make a firm judgment on whether it would kill MM.
And if Thor and She-Hulk at the same time can't punch through the forcefield, MM sure ain't.
Mental attacks would be blocked by Magneto's helmet.
So MM's greatest strengths are neutralized by Magneto, leaving someone not quite as strong, nowhere near as fast as Superman against him. Magneto then finishes MM off with a solar flare that sets him on fire. And because Magneto is pissed by all these DC threads, there's enough hate behind it that it would still ignite MM's phobia of fire.