Originally Posted by ThePowerCosmic
It doesn't have to be a sonic attack, just something to keep him down. I wasn't saying that I wanted it to be exactly like that clip, just similar.
The difference is that the submarine and onslaught of nuclear missiles weren't constantly barraging him with attacks as they grouped up on him. To manipulate metal, Magneto has to put some concentration into it, but concentrating would be hard to do when you're constantly getting attacked by Sentinels. Sure he would crush some of them, but eventually they would probably get him down.
I agree with that. If they were able to come en masse, relentlessly, he would at some point be unable to fight back against them all at once. As with any group attack on an individual.