she only thought she was killing him. the blizzard didn't hurt magneto except in a psychosomatic sense. that doesn't really count. that's like me saying "i almost toasted my pop tart by putting it in the freezer."
anyway, magneto tore up the entire team in that issue, and mesmero, and flew everyone transcontinental in an abandoned railroad car. at least i think it was a railroad car, i don't quite remember. that one don't count...
magneto could kill storm in an instant if he wanted to. an instant. there's really no way around it.