I did this in about 20 minutes total.
I just started by killing the brittlebones on the main floor and got a message right away saying that the shaman had taken notice of me killing them.
I continued killing them just in the main floor area. On the 3rd wave the deathwraps started to spawn. After I killed the 2nd spawn of deathwraps ( again just staying in the center of the main room killing just those that I could pull to me) I got another message stating that the deathwraps had all been eliminated.
After about 30 secs Tralb (who is up above you on the balcony the whole time just non attack-able) became attack-able, I ran up and killed him and that was that.