Solo'd as lvl 60 Hunter.  The trick in the final room is to draw the first batch of 4 buzzards out, with the goal of killing at least 1 before dying.  After you die, come back and kill the other 2-3 left, which will have less attach power as a smaller group.  No matter if you die once or twice before killing this group of 4 buzzards, come back to the room and SLOWLY inch up to the crystal in the center of the room.  You don't need to engage any of the buzzards to your left or the ones situated behind the crystal.  That first group is all you need to kill because you can obtani the Hive-Zore rubbing by just getting somewhat close to it and not right on top of it.