From his home on Asteroid M, Magneto leads his own Brotherhood of Mutants against Super Hero City. He is the Master of Magnetism.
Magneto uses his control of magnetism to summon a huge metal object, which he then throws at the nearest hero.
Once that big metal object has exploded, it breaks up into a bunch of smaller objects... which Magneto then launches at his target.
The master of magnetism shoots powerful electomagnetic beams from his hands. Anything that gets hit will take big damage.
Magneto takes forever to activate this big field that slows everyone down. If you attack him during his wind-up, it may stop him.