Nether protection is gone sadly, and I never got around to testing something. The Cataclysm-era Nether Protection worked as such: When you absorbed spell damage via any effects (nether ward, power word shield, whatever), you got -30% damage reduction in damage taken by that school.
What I meant to test was what happens when you get hit with a dual school spell? For example, if I put up a nether ward and get hit with a frostfire bolt. Do I:
1. Acquire only fire or frost protection?
2. Get protection from both fire and frost?
3. Get buffed with protection from only spells that are specifically frostfire damage, like more frostfire bolts or frostfire orb?
Anyone happen to know the answer to this?