I tried this for the first time with my Ranger and got wiped out by the mobs – badly. After reading the advice to focus on the summoners, I did that on my second try and it went very easy. As soon as the courtyard mission popped up I went after them (there are only two) – ignored everyone else until I killed them. After that the rest of the mobs were easy to mop up. Give it a try and see if it works for you. Good luck!