I think it would be better if you thought of the "Boss" more as a player, and everyone else as the enemies they have to get through to win. One hit kills might be viable if used against people who have unlimited lives. Perhaps you could get someone to make you some output events to change a team's respawn time, so you could decrease it with each point capped and make the game progressively more hectic. Just throwing ideas out, here, but you should totally try it.
