At the very end of the mission
End of the Line you're tasked with defending a rooftop. After a few minutes you have the option of calling in the AC-130 with
. Doing so will take you to an aerial view in black & white with red diamonds showing the enemies.
Try not to kill anyone before you can control the AC-130, if you kill too many, there won't be enough. For this reason, playing on a lower difficulty will let you survive longer leaving more enemies alive for the AC-130.
Warning:
You only get one shot at this. If you don't kill 25 enemies in your only use with the AC-130, or think you're running out of time, restart checkpoint
as soon as possible, as the game will save when you're back on your feet and you have to replay the whole level again.
Shoot as many as you can, changing weapons with
to avoid having to wait to reload. Don't wait to see if the shots kill your target, fire and forget and get ready on your next target, you don't have a lot of time.
Also, don't shoot the balloon.