What I recomend for the last level is for the firsy wave of hitting bad guys use a shotgun to take em out fast, for the next wave use the twister maxed out to push them so far back that they cant shoot, For the third wave of flying hitting guys use the twister so they cant get at you or the shot gun. Then finnaly I don't know because when i got to level 30 I chose some random perk instead of the 1-up perk so now im screwed when I got to the agents.