Originally Posted by
Captain Morgan
Really, the only question is whether the ring can corrupt Magneto.
A. Would Magneto be susceptible? I'd think so. He has strong will power and telepathic resistance, but I'm told either of those things really apples with the One Ring. He's also definitely someone whose ambition and negative emotions can lead to catastrophic results. See... Like, his entire career as a super.villain.
B. Will the ring have enough time to corrupt him? I have no idea. I don't know how quickly the ring affects people, from what distances, or whether holding the ring in a magnetic field is the same as holding it in your hand. I'm also not clear when Magneto even becomes aware of the ring or his starting distance from it, both of which seems like relevant factors. I'm not sure if it is better or worse if he's told about the ring before he's in proximity to it.
He's certainly physically capable of throwing the ring into Mount Doom, or the sun, of whatever. Zero question there. But having the opportunity to destroy the ring wasn't a problem for Isildur either. It didn't seem like he had the ring very long between cutting it off Sauron and standing over Mount Doom while being begged to throw it in. (Was that scene invented for the movie?) I suspect that while Magento is way more powerful than Gandalf, Erik's motivations would ultimately make him easier to manipulate.
Edit: Again, forgive me for using movie canon here, but I've seen it more recently than I read the books. But Gandalf was technically exposed to the ring here and there for decades: whenever he went to visit Bilbo. I don't remember why the ring wasn't actively corrupting Gandalf in that time, but I suspect that if a fish as big as Magento came over for tea, the Ring would get its hooks in sooner.