I can''t find it either, and I''ve looked all over. I remember it was just a bounty board during beta. It looks as if it may be glitched, but I could be wrong.
The zone is still there, as is the boss. I even tried going in a killing a few to see if made it pop (like Harda), but nope.
I've checked all around Kass City, all around the two camps before the Dark Temple and all around the Dark Temple.
It's no where to be found ...