Now that you're in Lazarevic's compound, you'll need to retrieve find Schäfer, get the dagger and locate the secret entrance to Shambhala. This is easier said than done, with the numerous troops around the area. It will be a combination of fighting enemies, crossing buildings and rooftops, and using stealth kills to your advantage. Toward the end you'll even have a puzzle that requires the use of your journal.
The first building
The chapter begins with an ambush. Grab cover behind the wooden railing right in front of you and start taking out guys, beginning with the laser scopes. The guys come from both sides and are reinforced by more enemies coming from above. After you clear the first wave, there will be a brief respite, then an RPG gunner will come down, so take him out. There's another guy with a missile launcher above and to the right of you, so head away from him along the available cover, until you turn the corner at the end of the room and can take him out. Head around to the stairs, and another wave will start. Take out the guy coming down the stairs, then face the opposite direction across the building and get cover to start taking out the bad guys over there. When you've taken out the last of them, two more guys come from the wall across from where you entered. Take them out, then head upstairs and kill another guy across the building. Head around the inside of the building along the wooden walkway and enter the room at the end.
Go through the room and out in the hallway, then go into aim mode and walk toward the next room ready to take out the guard that pops out from the left. Keep going around until you come back out into the main part of the building, then head up the stairs where you'll find Schäfer. After the cut scene, you and Elena will split up, with you going to the tower after the dagger and her looking for the secret entrance to Shambhala. Head down the walkway in the direction you start out, and cross the beam at the end to another platform. Jump across to another walkway, then cross another beam and jump to still another platform. From here you can jump out to the rope dangling in the middle of the room. Swinging in the direction you jumped, pick up the Tibetan Ritual Vase, then start swinging to the right where you can jump to the boards on the pillar there next to another platform. Head across the beam at the other end of that platform and go out the hole in the wall where you can jump to the next roof over.
To the tree
When you land up there, some guards will coming running out, but just stay crouched where you are and wait for them to start walking around. The guy close to you stops facing the other direction and the far one patrols around in the circle, stopping for a bit while facing the other way also. When the far guard isn't looking, run around the concrete rubble and stealth the guard closest to you, then get cover behind a wall and go for the next guy as his patrol dictates. Head into the building, then climb out the window on the other side of the room. Go down and to the left to drop down to a wooden landing. Go partway down the stairs, then hang off the side of them. Shimmy down the next landing, then around and down the next set of steps to the cliff below the guard. Climb up and ascend the ladder where you can stealth grab the guard. Alternatively, you could just shoot him, but this isn't stealthy and if you're unlucky one of his buddies will come down to support him. On the wall beside the guy at the top of the ladder, jump to the white stones in the wall and take them up then back around across the landing you were just on and around the side of the building. Here you can swing around to another platform, then jump across to the roof below you. Head around the side of the building to witness a firefight between some of Lazarevic's men and an unseen enemy.
Drop down to the roof below, then to the ledge below that and take some cover down on the ground or up on a little stone ledge right above the ground level to watch some of the snow beasts bounding away over the far rooftops. After this the remaining guards start skulking around, so it's time to go stealth them. Follow the closest guy along the side of the steps with the tree at the top and take him out before he reaches the other side. Head around to the back of the steps in the direction he was going, and push the guard back there off the rear cliff. Keep going around the other side back in the direction you started from and wait for the guard over there to turn his back to you. Run up to his crate, grab some cover behind it and stealth grab him over it. The last guy walks back and forth down the middle of the courtyard, so go after him while his back's turned and stealth him as well. At the top of the steps across from the tree, turn back around and go along the walkway on the right. At the end, jump diagonally across to another pathway where you'll find the Tibetan Conch Horn in the back corner. Grab it and head back up the steps, but this time continue on in that direction around the corner where you can open another door.
Get to the tower
This next area is going to be very tough if you don't get into good position right from the get go. Drop down the first ledge and hop the low wall, then go down some steps and climb up the ladder on the right. Cross the small landing and jump up to the next one, where you'll catch a glimpse of the two armored chaingunners down in the courtyard. They don't look up, so as long as you don't try to shoot them, you can continue unnoticed. Your goal is to get to the platform ahead and below you where there are a couple RPG - 7s. From where you are, jump to the red stones in the middle of the wall on your right, then jump over to the platform on your left. Go up and drop down the hole up there to the platform below and grab an RPG - 7. Make your way to the edge and start blasting them. Note that pretty much as soon as you do, you'll meet retaliation from both the gatling gun users and their reinforcements. You won't be able to kill the armored guys with missiles alone, so finish them off with your other weapon (hopefully the Desert - 5). After that, grab the weapon you dropped when you picked up the RPG - 7, and get cover behind the stone block up there. Your first priority is to take out the guy with the laser scope directly across from you, then the RPG gunner down at the bottom, after which you can pick the rest of them off at your leisure. When they're all taken care of, including the armored shotgunner that comes down the steps behind you, go down to the bottom and take out the sniper up in the window in the building at the end of the courtyard.
You need to get back up to where you went originally, meaning up the ladder where you came in and over to that far platform. This time, at the edge before jumping to the red bricks in the wall, look up above you and shoot down the treasure there. Pick up the Bronze Oil Lamp, then go to the red bricks and back over to the far platform. Don't go down the hole this time, but instead go down the stairs off to the side, which leads to a platform next to the window where the last sniper was. Climb up into the window and go inside. As soon as you get in, look to the center of the ceiling and shoot down the next treasure. Turn to your right and jump down to the broken wood next to a piece of wall below you. From there head over and claim the Ancient Sword Guard while Elena asks you about the snow beasts. Continue through the building and up the stairs at the other side. Jump the gap at the top and head outside.
At the other side of the roof, climb the white stones in the wall up to a ledge. Climb right along the ledge and watch the soldiers run around below you. Keep going around and pull yourself up onto a ledge at the other side. Hop down to the ledge below and look under the walkway above to see a treasure glint on the left. Shoot it down to retrieve the Tibetan Coral Earring, before going back up to the ledge above and continuing on. Jump to the red poles sticking out and take them all the way to the end, where you can climb over to the open window in the wall. Climb up into the window and jump across to the pathway across from you. Go around and climb up the dressers in the other corner to the top of the structure. Take the beam back to the roof that's not underneath a ledge, and drop down over the side. Shimmy over to the statue there and pick up the Tibetan Square Ghau, then climb back up and jump to the ledge across the gap in front of you. Up on the ledge, climb the white stones on the wall up and to the right and enter the tower.