I am trying to figure out how Resistant Hide works. This Armor always prevents all damage from Acid Poison Electricity or Fire. My Dwarf Wizard was wearing this armor while standing on Acid terrain created under my by an unfriendly elf Wizard. I did not move because I thought I was protected from all Acid damage. The Acid damaged me and discarded my Resistant Armor. So I think that my definition of ALWAYS and ALL are different from the games.
No, acid terrain discards all your armor (discards are not damage), then does acid damage now that you're defenseless.
Yes, specifically because lava does not cause you to discard the armor. (Thus if acid terrain didn't cause a discard it would actually work there too.)