I just found out this trade existed:
So it has the Magneto War, which is the storyline where Joseph kicks it, as well as my personal Magneto Rex which is just this crazy Magneto, Rogue and Quicksilver story and a must-have for any connoisseur of 90s superhero soap or Rogue awesomeness. It is sadly discontinued, but fortunately just about everything in it is available online if you're up for dealing with Marvel's confusing digital strategy. I'm just amazed it's out there and I never saw it. Those storylines are two of my favorite rereads in X-men comics.
This new knowledge of my own fallibility brings another question to mind: Have they ever collected Dark Seduction, the Magneto in Genosha-focused storyline that involves Polaris and Quicksilver, in trade paperback? That one isn't up in digital comics, and unlike Magneto War and Magneto Rex I wasn't able to read it when it first came out.