In Act V: Part I, you will not always be able to destroy the generators. However, after he is done, he will create a magnetic vortex of death. Go to where the fuse box was that would not work on the roof and hit it. A trap door will fall down and a possible "Strike: attack message will appear. Go through the first door and to your left to find a switch (Animal Senses may help). Another door will open. Go through it. When people appear, go neat the vortex. Debris will fly, but try not to get hit. Have them die near the vortex. That is the only way to stop the vortex.

During Act V Part I, when Magneto creates the twirling vortex take one of the enemies one by one, get them in the strike mode, pick them up, stand at the corner of the wall so you do not get hit, and press (Punch). This will kill them, and put them directly in the path of the vortex.

In Act V:Part II, it gets more difficult. You will have to get on a ledge where Magneto is near and do a diving slash. Do it a few times and you will see Logan attack Magneto and fall to the ground. You can get some attacks in. After a while, Magneto will try and gain energy in this area. You can mess him up there. Repeat this process to defeat him.

Stand on the ledge above the small round platform with "strong magnetic field" markings on the wall nearby. Magneto will attack you. But avoid these and he will eventually settle onto the small round platform. Jump down and attack him. When he flies away, move back up onto the ledge and wait for him to settle again.

When facing Magneto for the second time, hide in a corner and wait for him to stop attacking. Then, find the place where he gets power. He should have a wavy-looking tube around him. Run up the stairs by the tube. Walk through the tube up to Magneto and start to beat him up. He will try to attack you, but just keep hitting him. This will kill him very quickly.