No one has posted anything regarding the final fight here, so I figure I would at least give a little bit of information from what I discovered.
Level 105 Rogue, mostly group geared w/ raid weapons. 100k hp w/ self buffs and Surely, 2400 AC. Max hit I saw on me from these guys was about 6.5k, average seemed to be 2k-4k range.
Ok, so every time you kill one of the fake Skinwalkers, two more spawn. I didn't notice anything immediately that allowed me to decipher which was the real and which were fakes. I did notice, however, that one would summon a pet. I'd be willing to bet that it's the real one. This is significant in the fact that if you're kiting, he'll stop to cast.
When the fake ones spawn, they will return to the exact loc that they spawned. If you're someone who prefers solo/molo, you need to pull them off the ledge. In the event you die, they'll stay away from up top, and they are not tethered together, meaning that if you have 6 spawned down off of the ledge far enough away, they won't aggro if you get past them and attack the ones up at the chair. Due to this spawn trick, I was successful in keeping the real one separate from the fakes (after dying a couple times), and then proceeded to Counter Attack/Rogue's Fury disc him. Once the real one is dead, the fake ones despawn.
Sorry if my explanation seems broken, I'm typing this up on a whim mainly to give folks an idea of what they're up against for the highest tier instance.
Most mobs were 80-85, Skinwalkers were all level 89.