I took 73 SK, 71 chanter and 71 druid to kill these 3, I got 2 of them ok, but with Tehana Elsent mezed I took SK over, taunted, and attacked. I saw the message that "Tehana Elsent has been awakened by.." and then she was gone, no gate or anything, just despawn. Looked at the time and it wasnt even 2 AM yet.
I'll come back again and see if I can just get the last one.