Help on bonus round

Hi guys, I'm new here so I hope this is in the right sub forum. How do you survive for longer in the bonus round? I managed to survive 3000, with a hitman-shadow carry but the main weakness of this is that I can't seem to overcome are the bosses that spawn (sometimes in groups) which just tank everything and allow the other creeps to run past. Suggestions? ps Andy - this is a great game for people who enjoy more complex mechanics in games. Keep it up!

Welcome! I've managed to survive longer by using the withered set on a very fast and very high luck mr. iron. he just sends the big guys back over and over again until you whittle them down.