Theres one power that makes this trial very easy, and its Group Invisibility. A well coordinated team can group invis and each set off to a different stone (you know, the things that open the door). This way you can avoid all the pain the the mai.. only room in the trial before the AV. Its then a case of taking on the AV himself. Again a good team can do this easily.
So with the right team its a very simple TF with minimal risks. I dont know how they've changed the lvl for it now but when I did it with my alt I was lvl17.