The mesmer boss is 50/50 but usually we end up killing only ourselfs, sometimes it goes so badly that nothing dies except us :O. Mind Wracks.. for everyone!. Granted, i've beaten him but not without deaths. I know, i should probably bring my own monk heroes instead.. but.. i like to use Ranger with Winter because of the endless burning they're using, gah.
Warrior boss.. well this guy hit me with Counterattack for 214 - twice in one second. I've beaten him too but most of us had to use our rez. sigs with high DP.. I tried to do Hit & Run attacks today but it wont work that well.. "You're all alone!".. pretty much ends it.
Ritualist boss.. uh uh. Not that he does anything to harm us directly, but his troops turn almost invulnerable and.. totally clueless how can i win him

Dervish boss is just one-shotting anyone with DP. I was hit for around 400


Ritualist & Dervish, that was brutal. -.-
Okay, i'm done sorry about the long post. So.. how have you guys beaten this area?