Ranged attackers. Fast attackers, and attackers who can go invisible. Shoot past Tso and his minions and get into that inner room as quickly as you can. Use AoEs to damage as many of his buddies guarding the chicken as much as possible. Sneak attack at least two of the chicken's guards; if you get them down early enough you can more readily threaten the chicken.

Have lots of healing. Don't be afraid to use it. As soon as you beat his minion in the room full of pillars, heal yourself if you're at all wounded. You won't have time if you go into the next room.

Be really really lucky.