|2||Determined what to do with Quiet.||Mandatory|
|3||Neutralized Quiet without hitting her with lethal weapons.||Optional|
|4||Neutralized Quiet with non-firearm attacks.||Optional|
You will automatically begin this mission whenever you step foot in the Aabe Shifap Ruins area, which is west from the Serak Power Plant. It seems that this only occurs if you receive the cassette tape about Quiet, which usually happens if you finish all of the other main missions prior to this. Note that you will pass through this area on your way to the Serak Power Plant for the “Make Contact with Emmerich” Side Ops mission.
As soon as you enter the ruins area, you will come upon sniper fire. After the cutscene ends, you will have to do battle with Quiet. She will always start on the ruins, so use your binoculars to mark her. If you’re having trouble, look for the glint off her sniper rifle’s scope. Once you’ve marked her, make her shoot by standing up and then quickly ducking back down behind cover.
This will give you a few seconds window to shoot her before she is able to get another shot off herself. Upon hitting her, she will run off and disappear to another spot, making you lose your mark on her. It might be challenging to find her again, but the binoculars mic will allow you to pick up on her humming, so move it around until you see the mic meter fill up.
The battle will continue like this until you deplete either of her life bars. This will cause a yellow marker to appear on your screen, so quickly make your way to find Quiet on the ground, unconscious. You have a choice to make here, as you can either kill her right there, or if you wait long enough, Snake will holster his weapon and you’ll be able to extract her via helicopter.
Very Easy Method
There is a method to finish this battle very quickly, without even having to move from your initial position. As soon as the battle starts, try to get a mark on Quiet, which is simple because she always starts on top of the ruins. When you do, call in a supply drop on her exact location, baiting her into shooting at you until it finally falls, taking half of her blue health bar. Do this one more time and you will win!