Well, it could be an original character who was hidden away from Magneto for some reason. Maybe a human - mutant hybrid that Magneto didn't know about. This son could have powers that are not fully developed at first, and through his encounter with Magneto, he starts to discover and master his abilities. He could be a character who was raised by a family that was against Magneto's ideas, so there's a lot of conflict when they meet.
Overall, Magneto is a major powerhouse in comic vine. His magnetic powers give him control over metals, and he can use that to create devastating attacks and defenses. He's also highly intelligent and strategic, which adds to his strength.