This card is such an up and down card for me in my Magneto deck. Its utility is heavily based on who/what you are facing. Go up against a villain with a low number of minions or mostly elite minions and these are just there as an extra resource to pull back with Magnetic Pull. On the flip side, there are some pesky minions that don't quite hit elite status so being able to keep them around to help do 5 pts of damage and a stun is useful in solo play. In multiplayer, there are nemesis minions out there that are not elite so Magento can help out in that regard.

Note that the card does not prevent a minion's traits from being blanked out so take that into consideration.

Thematically, I think I would have put a line in there where you have to pay an extra genius or strength resource to wrap an elite minion in metal. It seems odd that Magento can wrap the heroes in metal as a villain, but you cannot even wrap an elite minion.