Holy mother of duck, finally!
The +2 arrows made the difference, that and a shitload of potions guzzled down, it was still a tough battle and had to try several times again but at least it wasn't hopeless like it was yesterday, with my main dps out it was pretty much unwinnable. The trick is to take out the 3 mages that spawn behind you asap, I'd say 70% of the difficulty of the fight is because of those fuckers, they dispel all your buffs, they immobilize/charm/mind-fuck your guys if you don't take them out in a heartbeat, and since I couldn't take them out fast enough with my mediocre dps in previous attempts I just hurled bomb potions at them with my monk and warrior while doing dmg with my archer as well, the problem is that my party got caught in the aoe ''friendly fire'' of the bombs a bit, but desperate times call for desperate measures, once the nasty fuckers were out of the picture I guess I got lucky with some rolls because still no enemy made it past my ''crowd control'' Maginot line at the door, most of them were unconscious and rooted thanks to stinking cloud and web. At this point I just kept doing dmg with my archer while sorcerer did aoe dmg on the door area, a nasty wave spell with my druid did a ton of dmg and I also managed to find a role for my useless monk as potion bombs thrower, I unleashed hell on that door, still Xyanuenoaw was still pretty much unfazed and came forward, thankfully my tank was well buffed and enraged and well supported by my druid, so he was able to tank her while my archer did dmg.
By the way, what the hell that green cloud spell Yxunomei throws at you does? Damage over time I guess?