I remember a fight scene very early on in the 'All-New, All Different X-Men' where Magneto is defeating the new group with ease. One of his final attacks has him fuse ferrous dust particles to Banshee's skin, trapping him in a skin-tight suit that blocks his air, although Cyclops manages to save him. My question is: If Magneto used this power on Paige Guthrie (Husk), would her powers allow her to escape or would the husked skin just become trapped in the metal with her, since the metal is more of a suffocating death- trap than a normal suit?
Husk's powers act like any animal that can shed/molt (Ecdysis) its skin, like many insects or snakes or vertebrates. That is, the outermost layer of skin detaches from the next, fresh layer. At that point, the animal (in this case Husk) has to work its way out of the shed layer. Husk tends to rip it away (because it's normally her normal skin), like an extra layer of tissue paper. Ever peel after sunburn? It's basically like that. Like an extra layer of tissue paper, it tends to be very thin and fragile.
It also for some reason makes her clothes just as weak (ahhh, fan service is a mutant power apparently).
That said, if Magneto covered that outer layer with a layer of magnetic powder/particle, it would really depend on how the writer decides to settle the fight. Either the magnetic particles would be unaffected by Husk's power (unlike her clothes) and stay when she tries to rip that layer of skin off (Magneto overpowers Husk), or the particles are affected (Magneto needs to think of a new strategy or get knocked out).
A creative writer would know that Magneto can just make the magnetic particles reattach to Husk's new layer, and either rinse, lather, repeat until Husk passes out due to her 1 hour power limit), or the creative writer could make Husk shed into a Anti-Magnetic skin, negating any immediate affect by Magneto.
In short, as any comic, it depends on Plot needs.
It would depend on the situation. For example, if Magneto was to simply form an airtight, steel ball around Husk, then she would easily be able change into a form with either a.)super-strength or b.) that has acidic qualities that can burn through the metal. However, if Magneto were to use the metal dust attack he used on Sean Cassidy (Banshee) in Uncanny X-Men # 104: The Gentleman's Name is Magneto, things might turn out differently. Here's why: When Magneto uses this attack on Banshee, he calls it a form-fitting coffin, fitting since the metal has Banshee unable to move, scream, or most importantly, breathe. Now, when Paige husks her skin, one of the drawbacks is that she has to pull the skin away before the new layer can be revealed. Therefore, if Magneto were to employ the same method as he had on Banshee, she would most likely need to be saved, unless she somehow managed to husk into a form that the metal could not cover before it had completely ensnared her, like her acid form, which would melt the metal.