Magnetic Metal Storm

This deck aims to support Magneto's Wrapped in Metal with additional minion upgrades and strong basic attacks.

Note that there are no synergies between Magnetic Missile and the Aggression minion upgrades other than if the upgraded minion is the one taking damage (and usually you'll want to target the villain instead, though there are exceptions). Gatekeeper triggers when the upgraded minion is defeated and Suppressing Fire when you attack and defeat it, while Magnetic Missile discards.

However, Wrapped in Metal is still an upgrade on a minion so Surprise Move gets its extra damage and ready. Using that should be rare as it's generally better to leave that minion around until you can use Magnetic Missile, but sometimes slapping Suppressing Fire or Gatekeeper on a minion that's wrapped up can make it worth it taking them out the old-fashioned way.

Marked makes Metal Shards more useful against weak minions since you get overkill.

Other than that, the deck is pretty straight-forward. Give Magneto a Hand Cannon and blast away!

There are many minor alterations that can be made while still having the same basic strategy. If you're feeling lucky, Digging Deep can replace the double resources (though note that they don't trigger Magneto's Armor), and in a multiplayer game where you're more likely to have an upgraded minion around it can be worth to bring in Take That! which is generally too expensive and misses too often in solo.

The allies can also be switched out for your own personal favorites. I've stuck with X-Men and X-Force allies for thematic reasons, but there's no mechanical reason not to bring in Throg or Nick Fury.

If you want a stronger economy, Avengers Mansion or Deft Focus can be included, though the former is a bit expensive early on and the latter won't help you with that many cards.

If you want to more reliably get a bonus to Attack from Magneto's Armor, load up on physical resources.