Mine was kind of luck because the "Michael Jackson-looking guy" missed with his attacks and so did the dancers/assassains. This enabled me to move in and lay the smack down on them all. However, they still took a couple of my characters with them and it took me about 20 or 30 tries before it happened. This battle and the one where you fight Gafgarion at the gate of the castle always take a long time. I never seem to be leveled up enough.