Tough challenge. Been working on this challenge for around 4 1/2 hours. This was my first time getting to the final wave, so didnt have a strategy. For the 4th wave the strat was to use a stun grenade to take out the flying enemies, take cover and use a cigarette to distract the enemies, then move all the way to the back of the arena. If possible stun the tank and shotgun the back of it as well. Somehow the other enemies of that wave were also wiped out, which I didnt expect. Once I complete this mission I will probably record to commentary for the tutorial immediately, because I wont remember all of these strats by the time I finish that final challenge. Planning to make another tutorial for this game, but for the Challenges only.
Decided to throw this video in the rare Brutal Games Series since these challenges are starting to get up there in difficulty.