Magneto is not in the same league as Darkseid.
http://i31.photobucket.com/albums/c379/Doggydogg/DarkseidandMagneto.jpg
Originally posted by Femi32
The planet is the same as earth.
Read this and you'll see why nobody's giving Magneto a shot in hell.
http://en.wikipedia.org/wiki/Darkseid#Powers_and_abilities
Darkseid wins. The Omega effect are basically a deus ex machina of energy attacks...if anything could negate Magneto's forcefield, it would be that. There's no underlying science behind it...it just...erases stuff.
Additionally, as opposed to Superman, who has a readily exploitable weakness for Magneto to take advantage of, Darkseid doesn't have much Magneto can work with. Does he have metal in his body? Does he bleed? Does that blood have iron in it? Does he have electrical impulses? A nervous system? Unknown.
Magneto is a finesse character. Though typically underrated because it lacks flash, it's a good skill because it allows him to beat opponents with greater brute strength and raw power (like Superman), but it fails against people who don't have anything he can take advantage of (like Darkseid).