Fight Tartarus with a Banshee

In the last part of Halo 2, where you fight Tartarus, it is possible to fight him with a banshee. This may take a few tries but it is well worth it. In the part of the level where Johnson blows up the door with a Scarab, wait for him to blow up the door, then fly into the door. After you're inside the door, start flying upward and foward. You will fly over one wall and then get stuck inbetween two walls. When this happens, fly downward. Your banshee will end up in front of a door. At this point get out of your banshee so the door will open, then get back into your banshee and fly into the room. A few brutes will engage you but you can take care of them no problem with a fuel rod cannon shot. After they're dead, get out of the banshee so the next door will open and fly in. When you do this, a cutscene will show, showing Tartarus activating Halo. After the scene finishes, kill the brutes and then run backwards past Johnson. Your banshee will be sitting in the hallway, which you can go into and fly through the pillers to fight Tartarus with. Tartarus will call you a coward for doing this, but a few fuel rod cannon shots should shut him up.

Also there is a way of fighting Tartarus without fighting all those brutes before the cutscene, thus conserving ammo. This tactic is extremely simple. All you have to do is after Johnson blows the door, fly to the right and go inside the circle thing that is connected to the building. If done correctly you should skip straight to the cutscene with Tartarus and, if you are lucky, the banshee will be sitting in the hallway behind you. However if it isn't there just throw a plasma grenade at the four brutes, then ride that platform with Miranda Keyes and blast Tartarus with all that ammunition you just saved.