This achievement requires you to act fast. On the second trip to Hengsha Island, Faridah Malik will have a crash landing, and you will be attacked by Belltower mercenaries.
There will be a variety of enemies, in order of decreasing weaponry: 1 Box Guard, 2 Heavy Rifles, 2 Sniper Rifles, and a handful of Shotguns/Machine pistols. The important thing to remember is the amount of time you have before Malik dies is dependent on the amount of damage she's taking. This is not visibly shown. Incapacitating everyone before the damage threshold is reached will get you the achievement. If you do not eliminate all the threats before the threshold is reached, Malik will die.
Picking the order of your targets is essential. If you target the lesser damage dealers first, you'll find this to be pretty much impossible since she will die extremely quickly. Therefore prioritize your targets; the most important targets are the 2 Heavy Rifle troopers and the Box Guard (Mech).
The two Heavy Rifle troopers are on the ground floor, one in the very back and one in the middle. They will constantly be advancing toward the helicopter. The location of the Box Guard is hard to miss due to its size but its in between the two Heavy Rifles. There are two Snipers, one on the top floor of the building on the right, and one on the top floor of the building on the left. Normal soldiers will be littered around the construction yard.
The easiest method to get this achievement is to immediately go to the right and enter the right building (jump up to the second floor), then run to the end of the building before you reach the stairs. There will be a soldier on the way (who may sometimes be killed before you even get there), a soldier behind a pillar near the end to the left, and often times, a soldier coming up from the stairs at the very end (he doesn't always choose to climb the stairs though).
Go to the soldier behind the pillar at the end (before the stairs) and to the left, taking out everyone you encounter. Then look down to the yard and a little to the right and you should see a Heavy Rifle. Incapacitate him (kill him or tranquilize him). Quickly run back the way you came and half way back, look down on the ground floor. You should see the other Heavy Rifle trooper and the Box Guard. Incapacitate the Heavy Rifle trooper and throw an EMP Grenade at the Box Guard (you can reverse the order if you want; it doesn't matter as long as you do both quickly). Once the main 3 damage dealers are dealt with, you have a fair amount of breathing room.
- If you do not have an EMP Grenade, things will get trickier. Your first priority is still taking out the two Heavy Rifles. Then you either want to keep the Box Guard firing at you (By firing at it while it can see you) while you pick off other units, or you can rush the Box Guard and use your Typhoon Explosive System. One attack from an upgraded Typhoon should be able to take the Box Guard out. Beware that it self-destructs upon being defeated, which not only harms you, but may also kill other soldiers, making it impossible to obtain the Pacifist achievement.
If you're not already on the ground floor, hop down and start picking off the other units. Watch out for the 2 Snipers. They can kill you quickly. They're lower priority targets, however, since their rate of fire is low and your presence will cause them to fire at you instead of Malik. As long as you don't completely dilly dally, you should easily have enough time to save Malik.
It is possible to get this achievement while also maintaining the Pacifist achievement so long as you tranquilize, stun, or knockout all organic enemy units. If you're going for this achievement, it's advisable to use the Tranquilizer Rifle, EMP Grenade, and perhaps use a lot of nutrients for Takedown energy. You can do it with the stun gun too, but it's a bit easier with the Tranquilizer Rifle. If you are not going for a Pacifist playthrough, you can use the explosive barrels to your advantage.
You can also use cloak mode. Cloak, run at the enemies, stun/tranquilize them. Just keep your energy high to stay cloaked. As the enemies only fire at your last known position (the position you have been when firing) it's advisable to keep moving all the time. This is very easy on normal difficulty, not yet confirmed on hard. Using cloak, it is also possible to gain the Ghost achievement.
After Malik flies off, be sure to collect everything you may want, as you cannot come back to this area afterwards.
No one has yet proven to achieve both Ghost and Nonlethal while saving Malik.
Pacifist Confirmed on hard (9/13/2011): Accomplished this achievement on PC with the following gear/aug layout. Augs: GlassShield Cloaking System lvl 3, Energy Level Upgrade 1. Gear: Stun gun (4 Darts), P.E.P.S. (~4 Cells), 1 EMP Mine. This was accomplished starting with one "battery" of energy and without use of any consumables for either health or energy.
(3/29/2012): Accomplilshed on PC without using combat/stealth augs. Gear: Tranq Rifle (10 darts), Stun gun (2 darts), 1 EMP Mine. Accomplished by sniping as many enemies as possible from starting position, running up when Box Guard is dropped. Note: Box Guard self destruct will kill nearby unconscious enemies, unsure whether this breaks Pacifist, but is avoidable.
(11/09/2015): Accomplished on PC using only nonlethal takedowns and stungun, as well as three of the small energy restoration items. Immediately upon starting the firefight, turn invisible (have it maxed if possible) and run to the elevator. Take the two heavy guards out there before they can move forward. This will keep the exploding boxbot from killing them later. The rest is fairly straightforward, taking down those at the right side first, then those at the left. Just be careful not to do takedowns that can cause the snipers to fall down to the ground, as the fall may kill them.
Pacifist (Hard difficulty) WalkthroughEdit
From your starting location move forward and right off the raised area into the construction. Sprint toward the partly finished wall jump over it and move past the first pillar to stun the merc near the second. Continue forward into the next "room" then activate cloak and head left to stun the first heavy merc. Turn to the right (you are now facing the same direction as level start) and head toward the second heavy, after stunning him turn left and head into the construction for cover as your energy runs out (you are now de-cloaked). Turn left again to see Malik's VTOL and a merc with his back to you, stun him and turn to your left again heading back toward the gap between the two partly constructed buildings. The robot will drop near where you stunned the first heavy toss an EMP at it and sprint past it toward the ramp in front of you (slightly left of the robot). If you stunned anybody close to where the robot drops, try to drag them out of the blast radius so they're not killed when the robot cooks off. There will be three more mercs to deal with in this area, one by the ramp (either at the bottom or near the top as you reach the second floor) and two taking cover by pillars on the second floor. Use stuns and/or takedowns to finish them off then climb the ladder and deal with the sniper on the floor above. WARNING. The sniper is often near the edge of the building, along with an explosive container, so be careful so he doesn't die. Once you've finished with the sniper head over to the second building and make the climb to the third floor of the second building, where you will encounter another sniper, also perched on the edge near an explosive container. When all the mercs are cleared you will receive a message from Faridah Malik and see the VTOL take off.
Note: This walkthrough was based on having both limited energy and Stun Gun ammo, if you plan ahead and bring a full stack of darts and/or some recharge consumables this battle will become MUCH easier as you will be able to stay cloaked longer, use take downs more and take advantage of the faster reload time provided by the stun gun (as opposed to the P.E.P.S. which takes much longer to reload).
You can watch a video demonstration of the above walkthrough here with some minor changes to utilize one Tranquilizer dart to speed up the process. In addition, if you came into this fight without an EMP grenade, you can obtain one as shown later in the video to take care of the boxguard.