I recall the second mission the Saints Row 2 'Corporate Warfare' DLC. The first half of it was you and about ten rent-a-cops against about 200 gents in heavy body armor equipped with assault rifles and backed by APCs. Once you've done that, you are put into a helicopter to escort a series of trucks containing nuclear waste. This would seem easy at first glance, considering the helicopter has a machine gun turret and guided missles with infinite ammo. However, you not only have to kill the incoming vans carrying three of the aformentioned gents each, you also have to take care of rocket ambushes along the road before the truck gets there. Rocket ambushes will take about 1/3 of the truck's health, and the combined firepower of assault rifles and high-speed ramming from the vans will do about 1/8 health per second. I managed to finally complete the mission by playing co-op with a freind, so that I was in the truck, and therefore able to better evade and fight back against rockets and vans.