HP Ice? I have never seen a Terrakion in my time playing BW running HP Ice. 72 base SpA is so terrible that it can barely 2HKO Landorus-T with HP Ice. I think you're thinking of Mienshao? It has a MUCH more usable special attack stat then Terrakion, and can properly abuse use it to use Hidden Power Ice or Grass Knot. You should never run HP Ice on Terrakion, period. Waste of a moveslot.