This is a focused attack. Charge the weakest enemy by the door. Hopefully the enemies will move allowing you to pass into the room with the chicken. Ignore then you don't need to kill them to win but do watch your health. Do the same thing focus on the weakest enemy by the chicken kill him and move into the spot close to the chicken. If the enemy moves into the vacant spot during their turn just kill that guy too. The muskets don't usually move if you are in range. Watch your health and move into a spot near the chicken at your earliest convenience. You can usually do it within killing only a few of the enemies.
I was only able to win by hiring a lvl 55 swashbuckler. I tried your idea with my buccaneer but I died to a ronin champion in 1 turn and my crew was killed in 2 turns! Since most players go solo no one is around to help you fight and i never have enough money to heal them so I had wounded crew members by the time i got to Tso. I also blame the simple AI of enemies targeting the strongest enemy so I waste powers protecting them and barely winning.
