As all of their attacks are physical, single target attacks, only your knight should take any damage at all, and with Barbarossa debuffing, they should be taking about 400 damage from him and 1 from everyone else. Get rid of Praline and Barbarossa first, and do not tough Qada until everyone else is defeated if you can help it, so Dark Breath will do 0 damage. Use fairy ward to stop his poison.