Fighting Tartarus without fighting Brutes

There is a way of fighting Tartarus without fighting his pack of Brutes before the cutscene, thus conserving ammo. This tactic is extremely simple.

Instructions
After Sgt. Johnson destroys the door of the Control Room, go inside and activate your Active Camouflage. Then go straight to the door on the right side of the room before it closes. If done correctly, you should skip straight to the cutscene with Tartarus. Also, if you bring a Banshee with you, the Banshee will be sitting in the hallway behind you. If it is not there, throw a Plasma Grenade at the four Brutes, then ride the platform with Miranda Keyes and blast Tartarus with all of the saved ammunition.

On the other hand, if you get a Banshee through the front door, you can boost in the second door, thus skipping the Brute fight and going straight to the cutscene.

Trivia

 * You are able to fit a Banshee into the Control Room. To do this see Fight Tartarus with a Banshee