If I remember correctly it drains the targets Magika, so I think that makes it an Alteration staff :)
It's either Destruction or Restoration, I had a set of -100 Destruction/Restoration cost armor, and it never lost a single charge.
but it also never drained anything.
I had a set of -100 Alteration clothes on, and it never lost a single charge. It worked perfectly fine. I'm quite sure that it's Alteration.
I checked this out, and it is alteration and not destruction.
strange because I never used fortify alteration cost of any ammount (only total cost for destruction and restoration) and it never lost a charge for me.
What do you think?