I figured this out with a clan-mate first time we attempted this. 
We accidentally triggered a delayed spawn, and we wanted to know how we did it, so we kept experimenting till we found the cheese! 
Basically what the cheese is:
Round 2 and 3 have a delayed hive spawn, so you're able to finish off the bombs before the wizards and boomers come out to annihilate you. 
https://www.youtube.com/watch?v=iy5vm668VwA
						
					
					
				- 
   
	5 RepliesYou're sad if you need to cheese that room. It's the easiest room in the entire 34 POE