Got Pharos one time in my High level duty roulette so far (I am SCH iLVL 73) and found the whole dungeon pretty simple... until we reached Siren. We wasted the complete time limit trying Siren and i have absolutely no clue how to manage that fight.
Did not try it again so far, maybe it had to do with my DF members too... but now i am scared to hell each time i start a high level duty roulette...