Magneto has this power:

Controlling the Magnetic Fields: Opposing characters within 4 squares and line of fire consider Magneto adjacent for movement purposes.

How would a power like Charge work with that power? I assume if you don't have the symbol or Improved Movement: Characters, you would stop once you get 4 squares away. What happens if I begin within 4 squares and try to charge? I would have to make a breakaway roll and then complete the charge? Or would I move 1 square, become adjacent again and stop?

You would stop if you came within four squares of him in that situation, and yes, you would have to make a break away on a subsequent action if you're already within the four squares

Once you break away from a character, you can now move through adjacent squares of that character during that move, so you can continue to charge in at him without stopping every square.

So figs with flight symbol or Improved Movement: Characters can charge or HSS speed Magneto?

Correct. Once one of those figures is moving, they don't stop until you want them to.

Yes. Magneto can absolutely shut down certain grounded characters. On the other hand, he’s very vulnerable against anyone with wings. My Regenesis results bear this out.

That's what I meant. You would stop if you get within four squares of him if you had no way of ignoring him when moving, and then you'd have to break away from him if you were to try to move in closer at a later point, but only once...you wouldn't have to do it more than once if you were already within four.

One of my favorite things to do with him was to let people stop within four and then Running Shot backwards against that character. Hit them, and now they have to get tied up all over again!

I was actually curious about this myself. Sounds like my speedster keyword team is well suited to take ol' bell head down.

He plays a lot like Groot Thor, but he is even worse with the Plasticity.

Yes, I wasn't correcting you, I was answering the OP, and hadn't refreshed the page in a few minutes to see your response. And I plan on employing that very strategy tonight at our month 3!

If you have someone drop a barrier between you and Mags, you can cut around the corner and punch him.

Depends if they can ignore Characters.
Otherwise, they stop with 4 ro2 squares like any other character.
Of course, they can then make the second move (after try to make an attack and not find any target), braking away on a roll of 2-6, but they won't be able to attack him.

Hmm, he's going to really nasty if paired up with a symbiont.

I figured you weren't. I just wanted to clarify my own post in case it was worded in a confusing way to anybody. Your post made me realize that mine could have been construed wrong is all.

Maybe I’m reading the PAC wrong, but doesn’t HSS grant Improved Movement: Ignores Characters?

It does not, Hypersonic grants you I.M. double circles with a arrow through them. That allows you to move through squares adjacent to or occupied by opposing characters without stopping.