We don't "nerf" anything, we just fix. This could be: a) something got bugged: possible, but much less likely. Class mechanics aren't generally messed with, unless something was incorrect. Still, a fix on one thing could lead to something inaccurate on another, but then there would probably be reports in the Bug Tracker, much more specific than "arcane got nerfed, plz fix"; b) something got fixed: more likely to have happened in general. What you see as "nerfing" being simply fixing something that was performing beyond what it was meant to, and you were just too used to playing it "buffed" instead. We don't undo fixes because players liked it better before, you'll have to get used to playing the class the way it's supposed to be, if this is what happened.