I think that even at 85, only 1 mob in this zone will be 1 groupable. That is lorekeeper Bentlof. He was at 80. I seriously doubt you can 1 group 3 bro's. It takes a couple of good healers and atleast 3 people who can tank/kite adds. It might be possible to 1 group the undead event now, depending on how hard they swarm hit your person who triggers event, I havent tried it thought.
Bentlof is very easy to 1 group, however very long kill. What you do is have someone who can Feign Dead trigger him. He will spawn a add. When the add spawns have the person FD, then someone else in group go agro the add after it walks back to its home point so that person doesnt agro Bentlof. Then kill the add. Once all adds have been flop spawned and killed then you have a room of just bentlof for 1 group to kill easily.