Jigsaw is quite possibly the easiest fight in the game (if played smart). First, take out Jigsaw's jet pack. Simply walk over to a cargo crate. Make sure that you can see Jigsaw, but he cannot see or hit you. If you wait, Jigsaw will come to you. When he gets close enough, run under him. Then, just shoot his backpack and stay under Jigsaw. After a little cat and mouse, an intermission sequence will play. Jigsaw is now on foot. Jigsaw's way of defense are ten fast blasts and a large plasma ball. You will need to run in between boxes to throw him off your path. Run around until you see a guard, then finish him quick. The guard will drop a RAM explosive. These are used by walking up to a wall and pressing Secondary Fire once (while RAM is selected). The charge is now armed and ready for detonation. Get Jigsaw's attention by letting him see you. He will run after you. When he gets near the RAM, press your Secondary Fire again (maintain safe distance) and an explosion will blow off a piece of Jigsaw's armor. Repeat this procedure until Jigsaw falls to your punishment.