Commander Room

Boss Fight: Psycho Mantis

Meryl is being mind controlled by Psycho Mantis. She fires at you with her gun. Punch or throw her to knock her out, or toss a stun grenade at her. The fight with Psycho Mantis begins with him warping around the room while invisible and throwing explosive balls of energy at you. You can activate the thermal goggles when he does this to see where he's going and then attack him. The problem is that he dodges your shots and your punches because he can read your "mind" or your controller inputs. In order to get around this, plug your controller into another port. He won't be able to read your actions, so you should be able to shoot him! Whip out your FAMAS.

Stay low against Mantis when he sends the furniture flying.

After throwing a few balls of energy, Mantis will float to the middle of the room, where he's visible, and start using furniture and other objects in the room to attack you. Crawl on the ground while the furniture flies. When it goes away, you'll have a brief opportunity to stand up and shoot Mantis. Keep repeating the process. Go prone and avoid the furniture. When it goes away, stand up and shoot Mantis. When you have him half-dead, he'll take control of Meryl again and have her shoot you. Throw a stun grenade at her. Mantis will then attempt to force Meryl to commit suicide. Immediately throw another stun grenade at her.

From here on out, Mantis continues his pattern, alternating between using the energy ball attacks and the flying furniture. Keep blasting him with the FAMAS when you have an opening, and he'll go down. After Mantis opens the passageway, grab the rations on the way out and head to the caves.

Caves

Head to the right, and at the intersection, go south for some SOCOM ammo, and north for some rations. If you go into first person mode where the rations are, you can see where Meryl is waiting for you. Go back to where you entered the area, and go north through the snow. Crawl under the gap here, and you may see some wolves. The best weapon against the wolves is actually the M9. If you just kill the wolves, more will spawn in, but putting them to sleep keeps you from being harassed constantly. Walk north through the clearing, then hang a left to grab some FAMAS ammo. Now go back to the right, and then south. You'll see some PSG1 and PSG1-T ammo that you can't pick up yet. When you reach a dead end, crawl under the gap to the south, and grab the pentazem. Now go back out, and under the gap to the right, and meet up with Meryl. Grab the rations next to the door before leaving.

Underground Passage

Follow Meryl's footsteps.

Meryl will walk a pattern in the room to avoid the mines there. Monkey see, monkey do. Follow her footsteps, meet her again and you'll trigger another cutscene. After Meryl gets lit up by Sniper Wolf, you'll have to leave the area to find a sniper rifle. You can get one in the armory. Backtrack there and get it. You'll find a few changes in some areas, though. When you pass through the canyon, it's guarded by cameras and troops, and the laser trip wires in the cargo bay have been disabled. When you get to the armory, you'll find it's patrolled by a few troops as well. You should have the skills and know-how to bypass these dangers already. Make use of your toys, like cardboard boxes and silenced weapons.

Go into the room on the top left of the armory that has a level 5 security door. Activate your thermal goggles and crawl underneath the laser trip wires. Grab the PSG1. Make your way back to the area where Sniper Wolf shot Meryl, picking up PSG1 ammo along the way for the boss fight. Grab the pentazem next to the doorway.