Currently the Throne of Thunder Tier 15 Regalia of the Witch Doctor can't be completed with an Enhancement loot spec. I just needed the chest piece off of Animus to complete the tier set (heroic in my case). Under my Appearances tab, it showed that I could complete it with either of 2 pieces of armor: Hauberk of the Witch Doctor or Tunic of the Witch Doctor. Both show to be "Vendor" sales which means that it will be a class token drop off of Animus. It didn't register with me that it should have shown 3 chest pieces; 1 for each spec. So I took my Elemental shaman in and didn't get the correct token to drop of the 3 that Animus did drop (2 Vanquisher and 1 Conquerer).
Next up is my other Shaman, who is Enhancement spec. Animus did drop 1 Protector token and I clicked it expecting my chat to say "Regalia of the Witch Doctor completed". Instead I got a "Cuirass of the Witch Doctor has been added to your appearance collection". I checked the set tab and sure enough, the set is not completed. You can only complete it with the Restoration robe or the Elemental robe. It won't complete with the Enhancement chest piece since it is a short jerkin appearance. I have never seen it mentioned anywhere that you have to be in Restoration or Elemental loot spec to complete the set. I sent in a bg report since this seems really screwed up. So next week, back into ToT with caster loot specs!