After advancing through the mansion with Mona, Max is ambushed by her, knocking him to the ground with the butt of a Desert Eagle, and she holds him at gunpoint. She tries to pull the trigger, but finds that her feelings for Max prevent her from doing so. Some think that when the camera turned to Mona, Woden didn't want Max to die. After throwing the guns away, she is shot in the back by Vladimir Lem. Just before he does the same for Max, though, Alfred Woden leaves the panic room and attempts to disarm Vladimir, but is killed in the process. Max then attacks Vlad, who sets off a series of explosions in the mansion the cause the floor to cave in underneath them, and they fall to the floor. Vladimir runs away, leaving his gun behind.
The Panic Room
After getting up, and starting, walk through the door directly in front of you. Take a left, and shoot the man with the MP5. It is recommended to conserve the ammo of the weapon he drops to the ground. Use the desert eagle until you run out of ammo, then use the other weapons.
Killing the bodyguard with the MP5 will result in the panic room dropping through the floor. Immediately pass through the door and close it with the switch on the inside wall; the enemies running for the panic room won't be able to get in when the explosives go off. You get 4 painkillers inside the panic room.
When you hear a series of loud explosions, hit the switch again. All the enemies will be dead in that area, leaving you free to pick up their ammo. Travel further to the large hole in the wall and drop down to the room below. Be careful; Be sure to land on the metal sheet or risk taking considerable damage. Another commando will pop through the door, kill him immediately, as he will be ready to fire. Another enemy will be at the top, above where you dropped, sniping at you. You can ignore him at the moment, if you wish.
The Mansion Cellars
The rest is similar; kill, pick up ammo, and repeat. If you run into Vladimir Lem, do not engage him. He is heavily armed and invincible until the moment when he is on the scaffolding. There are multiple times you may run into him: At the very beginning, when he is making a run for the door, in a room where he sets off multiple bombs and fires at you to keep you in check, and the stairs where he is shooting at you from above.
In the second room you see him in, take cover until he leaves the room, then make a run for the stairs, as the bombs will start to go off, leaving you trapped in a dead-end. Run, as fast as possible, and use shootdodge to make the jumps, if neccessary.
This is the first active engagement between you and Lem. Take out the guards in the bedroom, and take the painkillers. Walking into the room with the stairs will immeditately result in a detonation, so you must use the wheelchair escalator. Activate the switch on the far left, then take cover and shoot at the commandos and Lem as neccessary. At some point, Lem will tire of your refusal to die, so he will use the cabinet as cover as he inches toward the switch. Be ready to hit it again. Once he sends it back upstairs, he will start shooting at you again, so quickly activate the escalator again and wait for Lem to leave. An easy commando will walk through the door; take him out, and use the wheelchair escalator to get up there.
This is the final battle between you and Lem. Lem will go into a monologue, however short, use this time to take out as many of the supports holding up the scaffold as possible. They are relatively easy, a single shot with any weapon should take them out. After taking one out, or after Lem throws his first set of explosives, run in a counter-clockwise direction around the center, taking shots at the supports when respite allows. Taking out three will be enough to make him fall.
Taking out the scaffold will not result in Vlad's death. He will survive it, and be more persistent with the explosives. Continue using the same method as before, except aiming at the supports attached to the spike over Vlad's head. I recommend using the M4 Carbine to take them out, as they will proof more difficult to take them out, often taking multiple shots from the same direction to be shaken loose. Be careful not to shoot a suppor back into its original position. Also, be careful about the explosives, even if you escape the rounds of explosives, you could fall into the holes that result from them.
Even after taking out the spike, Vlad still won't be killed from it. But he will move out from his cover, allowing you to take him out the old fashioned way. He is still heavily-armed so it is recommended that you use the rest of your bullettime to take him out. Enough shots with any gun should take him out. The best way to kill him is to do what Max said, to "give Vlad his gun back, one bullet at a time."
Once he's shot up enough, Vlad will rest his body on the spike, giving you some parting words before the scaffold collapses and he falls to his death.
On easier game modes, Max will then crawl back to Mona, who gives him her last words: God, I turned out to be such a damsel in distress! Before dying on the spot, as the police arrive on the scene.
On Dead on Arrival, Mona will survive the encounter.