You can definitely take down the Bishop at level 7, but it will take some cunning. For me, a big part of this fight is just keeping alexander away from you until the worm spawns so that they can hack at eachother.
Have at least two characters use teleport alternately on him so that he stays far away, and you should have no problems.
You could describe how your party setup looks, and exactly how your face is getting wrecked?
