To defeat Cobar, run and the grab the missile launcher from the supply depot at the bottom left of your screen. While hiding behind the concrete block next to the depot, throw grenades at his machine gun. This enables you to lock on to his missile launchers (which causes the most damage). In order to lock on to one weapon at a time, hold L + R while firing or throwing grenades. Once enough damage has been done with the grenades, his missile launchers will turn so that you may see the holes. You can now lock onto them. From this position, shoot the left one first. Fire two rockets as fast as possible and make sure that you do not miss. If you miss, restart. After both rockets hit the left missile launcher, you must run around a bit. Make sure that you reload after the first two shots. In between the rockets that he shoots at you, aim at his right missile launcher and get both shots off. This may be easiest from either the tall cement pillar or the small cement block on the right, as neither barrier breaks down with damage. In any case, do whatever is needed to destroy the second missile launcher. At this point, he should not be able to hit you if you are behind one of the cement barriers. Either grab the sniper rifle or the crossbow that you brought with you (if over ten shots remain), and go to the cement barrier by the left supply depot. While holding L + R, hide behind the barrier and focus on the mine thrower on the top of the machine or the machine gun that is tearing you up. Time your shots so that you are hiding while he is shooting and you are shooting while he is reloading. Try to destroy this weapon as fast as possible. Spider Mines may start climbing out before you are finished with the weapon at hand. As soon as you see the Spider Mines climbing out, run to the supply depot and get the assault rifle (or counterpart) and immediately lock on to the Spider Mines that are coming towards you. Only about five are released at a time, but you must kill them while they close to the Boss so that they do not explode near you. Tap L(2) to roll out of the way if they are about to explode near you. Try to kill the Spider Mine hatch before more come out. After you kill the left, run to the other side, as more Spider Mines will also come out of there. Repeat the previous step then kill off this side as well. Go back to the left cement barrier, refilling any life that may have been lost. If you are hiding from the machine gun, get directly behind the barrier. If you are hiding from the mine thrower, get to the back right corner of the barrier, but directly up next to it. Get out of the way of the explosions or bullets. Time your shots in between his and take out the remaining guns.