Damn this thread blew up since yesterday.
The quest item books that people keep finding are from the old beta version of artifact knowledge, when you first hit 110 you had to go around and collect 5 books to start your first artifact knowledge resource.
The cave under VH is part of the hunter class campaign.
Browsing through wowhead NPC database, filtering for undead and added in Legion, there's a weird abomination that shows up in HFC and Ulduar. Anyone been to HFC recently?
http://www.wowhead.com/npc=106848/abomination