Hi maybe this is useful to someone; the raid bosses Thesakar, Theor, and two others whose names start with T I forget right now, are a set of 4 that always spawn together. These bosses are always insta-farmed by someone, but you can still get them for quest, because now you only need to do 1 damage on a mob or be in party that does damage on the mob, and you get credit for the boss when it dies even if you or your party don't kill it. (ps this is a good way to raise some faction % quickly, by going to kill 1 kandiloth in hellbound, etc)
I had this problem with one of my chars, I needed more bosses, but I knew where these raids were, so I left him on macro with aoe skill at the spawn point, he did get pk once and moved away a few times but I put him back and within a day he had hit the bosses, and got credit for all 4, and completed quest all while staying alive afk
They are located just outside Gainak upper, if you run outside to the right, down the hill towards the jump point, just above the jump point between that and the gainak gate is a little raised area, and the spawn spot is between the rocks and the trees. Often there is a dead or watching toon on the spot for the person who usually kill it.