Re: Helmet that blocks mental attacks
OIF means Obvious Inaccessable Focus, and is a -1/2 Limitation. I would build the power as straight mental defense, as it pretty much seems to block any and all mental powrs. Thus depending upon the Power Level you are building Magneto at, his helmet would look something like this:
20 Mind-Shielding Helmet Mental Defense 30, OIF -1/2, (30 AP, 20 RC)
I would assume Magneto's EGO would be a 20 or so... and I could easily see him having worked with Xavier in his youth to up his Mental Defense without the helmet, which would mean buying 10-15 points Mental Defense without the Focus limitation. Assuming the math for Mental Defense hasn't changed, that would give Magneto 44-49 points of mental defense (30 from the helmet, 4 points for his EGO, and 10-15 points for trained Mental Defense).
I'm not sure how much extra DMCV would cost (I use 5th Ed rulese, and assume DMCV replaces DECV *shrug*)