At the end of level 3, you will get stuck in a large room with some goons, a pair of large rocket launchers, a pair of large ninjas, and a pair of bulldozers. This is no easy task. Strafe around all the commotion. Concentrate your fire on the large rocket launchers and the large ninjas. If you are playing as Grave and you have plenty of demolition shots, they should not last long. Just use the Gun Dance attack a few times. Keep shooting and earning more demolition shots to get rid of them if you run out. The problem is getting rid of the bulldozers. Run into a corner of the room. The bulldozers are too big to hit you in that small space and will stay stuck to each other in front of you, waiting for your punishment. If other goons show up, do not worry about them. Keep pressing Square without moving from your corner and they will soon stop emerging. Then, hold Square until your guns start to go aflame, and release to shoot some burst shots. Regular bullets do not work on the front of the bulldozers. When the front of the bulldozers explode, they are now vulnerable to any attack. Unleash your rage on them, without moving from your little corner.