Confronting Eliza Cassan

M1 - Confronting Eliza Cassan is a mission in Deus Ex: Human Revolution.

Go to room 404
After leaving Tai Yong Medical, you will be dropped off at the Picus Communications building to find Eliza Cassan. When you leave the Helipad to the door that leads into the building, you can enter the enclosure to the right by hacking the level 4 lock. You can also jump over the fence surrounding the enclosure utilizing nearby crates or, having entered the building, break into the enclosure through a weakened wall. The enclosure contains a few supplies and an ammo capacity mod.

Continue inside the building and Jensen will notice that the offices are empty and that there are abandoned items everywhere. You figure out that a fire alarm was pulled and everyone had been evacuated. You are welcome to explore and take everything you want. There is a Praxis Kit in one of the desk drawers in the main open office. When you are done, move to the objective and watch the cutscene where Eliza will talk to you.

Room 404 is on level 6.

Escape the ambush by reaching a lower floor
After the cutscene is over, you will be tasked with going to lower levels and finding where Eliza is held. The main open office area is now filled with Belltower soldiers looking for you. You can clear everyone out. There are also vents accessible from an office and a conference room near room 404. These vents will let you out on the second level of the main office. As there are fewer guards on the second level, this route is somewhat easier. After escaping the main office, you come to a lobby area patrolled by two guards. Take them out or hide from them. If you entered the lobby area from the office space, be sure to stop in to the Men's bathroom and pick up the Rate-of-Fire weapon upgrade there. You'll also find a vent which opens behind the bank of copier machines in the lobby. At the far end of the lobby is an elevator and an open elevator shaft. Either take the elevator down or, if you have the Icarus Landing System, you can drop down the shaft and crawl through a vent. The vent leads directly to the room with a unique eBook. Either way leads you to the main newsroom.

Alternatively, the arrival of Belltower opens several firedoors, one of which leads to a two-level server farm. On the bottom of the level of the farm is a weakened wall that can be used to get down to the newsroom. However, to get access to the newsroom, you must break through a second weakened wall, and this may alert nearby guards.

The newsroom has an upper catwalk system and a main floor. Both are occupied by more guards and the main floor has a turret. Located near a set of stairs connecting the main floor and the catwalks is a security hub. You can hack this without worry of being seen and use it to either activate or turn off the turret. Note that if the turret is made to attack the guards, one of them may trigger the alarm system. The newsroom is worth looting, as there are plenty of credits. A cubicle with boxes blocking the drawer contains a silencer mod. There is an Auto Unlock Device under the console behind the northeast staircase. Once you are done, continue down the stairs. There are two guards at the bottom of the stairs who can be taken out using the Quicksilver Reflex Booster augment. The hallways nearby are empty, and the two nearest rooms contain loot. The third and final room is your destination.

Get to and summon the funicular
The third room contains the funicular towards which Pritchard has been directing you. The room also contains two guards, a turret, and a camera. In the hallway immediately outside of the room, there is a vending machine. Moving the vending machine reveals a ventilation shaft that exits near a computer, which is the security hub controlling the turret in the room. The guards can see you while hacking the computer, so either block their view or time your hack attempt correctly.

Take out the guards or sneak to avoid them. Summon the funicular by pressing the button near its entrance. Pritchard will inform you that the funicular is on its way and that an alarm has been sounded. You must wait a while for the funicular to arrive, during which additional guards will appear. Beyond simply fighting it out, you can:
 * Make use of the turret. Use the security hub to hack the turret and let it take care of the additional guards.
 * Block the doorways. If Jensen has the Move/Throw Heavy Objects Augmentation he can block off the doorways using the heavy objects (which are closer). The closest objects that can be used are: The vending machine, the large container, the small container, and the turret. Alternatively, the doorways can also be blocked off by only using small cardboard boxes, which can be found on the previous floor.
 * Hide. There is the ventilation shaft mentioned above, another passageway running under the stairs leading up to the funicular, and a third passageway between one of the room's entryways and funicular itself. You can use these to conceal yourself until the funicular arrives. You can also put some large boxes right in front of the funicular doors and hide behind them. Make sure you can't be seen by the guard that goes upstairs. As soon as the doors open, you can sneak out unseen.
 * Takedown guards one by one. To get the most amount of XP, go back where you came from, to the main staircase labeled "Zone 6" - there are some guards along the way.

Pritchard will let you know when the funicular is halfway there and when it has finally arrived. When it has arrived, enter it and start the ride down. The button to start the funicular is on the righthand wall as you board.

Note: Not only can the turrets be hacked and set to attack your enemies, but with the "Lift heavy objects" aug you can also move them or carry them around. There are two heavy turrets to be had - one in the lobby and one guarding the funicular. The two hacked turrets can be taken onto the funicular this way and used to destroy all the Spec Ops soldiers in a few seconds of security turret dual gatling gun carnage. Same trick can be used in Singapore.

Get inside room 802-11
The funicular lets you out into a room with a camera and several crates. The exit to the room leads to a long hallway and is guarded by laser sensors. There is a security panel next to the exit. Hacking it will allow you to turn off the lasers. To do this, use an automatic unlocking device, or position the containers in the room (one tall container in direct line of sight will suffice) so that the camera cannot see you. Alternatively, once you near the exit, two guards will come down the hallway towards you. They will enter the room, talk for a moment, then one will leave while the other will commence a patrol. You can take down one or both guards and position their bodies near the laser sensors to deactivate them (though this may trigger the camera). Lastly, there is a weakened wall to the far left side of the exit. Breaking through this will grant access to a ventilation shaft that bypasses the sensors. Beware though, when the guards see the broken wall, they will go into alert status for quite a while, investigate the wall and then head back up the hallway.

Once through, proceed through another newsroom. There are two guards on a catwalk up above and several guards on the main floor below. It is not difficult to avoid them all or to take them all out. Also, make sure to explore the corner office (underneath the room with the glowing globe) where you'll find an unique eBook. **NOTE: If you choose to knock out or eliminate all of the guards in this room, you can still carry the turret(s) forward into the newsroom. If you choose to carry one of the turrets into the last newsroom, the turret will target and destroy the robot (if, also, you chose to disable the robot rather than make it a friendly).** After the newsroom, proceed down a flight of stairs (watch for the two mines on the wall) to a lower level. Another guard will be patrolling the hallway. Take him out or avoid him by going through the offices to his right. Those offices also contain the security computer for the hallway's cameras. Also, at the bottom of the stairs is a weakened wall, behind which is a hidden area containing loot and a ventilation shaft that can help you bypass the guard. Along the hallway are locked offices with additional loot, so it may be worth taking out the guard in order to do some exploring.

At the end of this area, there is a set of double doors with a level three lock. If you can't or do not want to hack this lock, there is a work room to the right of the doors that is patrolled by two guards. A camera at the far end can be disabled via a security hub on the left side of the work room. This room can be worth exploring, as it contains yet more evidence of how Picus is fabricating the news. Either way, once done, the next marker leads to an encounter with Yelena Fedorova.

Boss Battle Two: Yelena Fedorova
Fedorova is the second boss encounter in Deus Ex: Human Revolution. The fight takes place in a large octagonal room with four power generators, conductive coolant on the ground, and several large panels. Defeating Fedorova triggers a cut scene in which you discover the true nature of Eliza Cassan. She also reveals that the next conspirator is Isaias Sandoval.

Go to the chopper and extract
After defeating Fedorova, go to the landing pad and leave. ** NOTE: [Encountered in DXHRDC (see Fedorova Tactics below)] Once you've defeated Fedorova, the door through which you entered is now locked. You can hack this door (or use a AUD on it) to re-enter the previous areas (newsrooms, etc.) and resupply anything you can't find in the lockers here (though these are pretty well-stocked with loot). Also, hacking the door opens a door directly across from this door. Both doors now reveal long, arcing passages which take you to a room above the Boss room. The floor in the room is transparent, allowing you to look down on the Boss room. In the room you'll see a Level 3 security hub (Fedorova's) in the center, protected by a ring of laser beams and two ceiling-mounted Turrets. There are also 4 gas-filled cylinders, with attached valves; the valves are inert and you can't interact with them. However, you can shoot each cylinder and stay out of range of the dispersing gas until it dissipates. Tripping the lasers causes the Turrets to fire on you (there is no cover). Two ways to turn these off the lasers: [1] Standard - hack the Security Panel (Level 3) and 'Disable Laser'; [2] With Strength augment - Punch through the wall next to the panel, revealing a Breaker Box that can be turned off. You can then hack the Security Hub and turn the Turrets to 'Enemies'. Feasibly, if Fedorova follows you into this room, you could either shoot out the gas cylinders (only makes sense if you have the Rebreather augment), or the Turrets will fire on her (if you set them to 'Enemies'. **

Fedorova Tactics

 * Supplies are located throughout the edges of the room in lockers. Helpful items include:
 * Shotgun (and ammo)
 * Heavy rifle (and ammo)
 * Revolver (and ammo)
 * Machine pistol (and ammo)
 * Typhoon ammo
 * Automatic Unlocking Device
 * EMP Mine
 * Mine Template
 * The game can be saved during the encounter.
 * Fedorova attacks with dual SMGs, and by charging the player and using the Typhoon.
 * Between sets of three Typhoon attacks, Fedorova will activate cloak and circle the room to recover.
 * When destroyed, the power generators will discharge electricity through the coolant dealing ~90 total damage over time to anyone touching the floor and stunning Fedorova.
 * Both the player and Fedorova, or a combination of both, can destroy a generator.
 * Jensen is immune to electricity if he has the EMP Shielding upgrade for the Dermal Armor.
 * Fedorova can be tracked using Mark and Track, Smart Vision, the visual distortion of the cloaking field, her casting a shadow on the outer walls, or ripples in the coolant from footsteps.
 * Fedorova will parry any takedown attempt, dealing critical damage to Jensen.
 * Fedorova is vulnerable to headshots as well as EMP, concussion, gas, and frag grenades.
 * Setting traps using UR-DED or proximity mines works well.
 * Fedorova can be stun-locked with the stun gun. On Give me Deus Ex difficulty, it takes around 35 shots to defeat Fedorova. But stunning her just once and then throwing explosives at her, around 5 or 6 of them, will end the fight almost immediately after it begins. On normal difficulty you can stun her 20 times in succession and then hit her with a blast from something heavier for a more satisfying victory. (This strategy no longer works in the Director's Cut version of the game. The stun duration has been shortened, and it is now much shorter than the reload time, making a stun-lock impossible.)
 * Using the Typhoon Explosive System is effective but risky, because if Fedorova gets close enough she will use a Typhoon of her own. One way to deal with this is to equip Jensen with a stun gun. Once cutscene ends she will charge at you. Stun her, wait for the stun gun to reload and then use the Typhoon. Stun her again (if needed), then use the Typhoon for a final time. Two hits with the Typhoon is sufficient to take Fedorova out in the easiest difficulty level and three on the most difficult. Recharge your energy cells accordingly, prior to the battle. Note that the Typhoon will cause her to be stunned as well (although not as long as the stun gun), so if you're quick enough you can use the Typhoon repeatedly without taking any damage. (This strategy no longer works in the Director's Cut version of the game. The stun duration has been shortened, so she will simply run away from the player in the middle of the Typhoon's animation sequence, avoiding all damage.)
 * If the player has the combat rifle, upgraded with the target-seeking system, this fight is made remarkably easier. When she charges you, lock onto her and empty your magazine while moving away.
 * Reload canceling the heavy rifle is highly advisable during the battle, since it has a very slow reloading and Jensen can't sprint during it leaves him vulnerable to Yelena typhoon attacks, tapping the cover button near a wall just 2 seconds after reload animation starts will make the gun  reloaded and ready to fire
 * For entertainment, you can bring the turret down the funicular to assist in the battle. While the initial "use" command will leave the turret isolated behind the door, if Fedorova's initial attack can be fended (e.g. with a shotgun), the door can be re-opened via the keypad. Fedorova attacks the turret with her Claymore/Typhoon system if her charge brings her close. However, if she engages with her dual machine pistols, she remains stationary for a significant amount of time.
 * The P.E.P.S. weapon stuns Fedrova for an extremely long time, but it takes almost that full amount of time to switch weapons after firing the P.E.P.S. Fedrova will inexplicably continue to block any takedown attempts while she is stunned
 * In The Director's Cut, there are hallways on the sides of the circular room that will take you to an upper floor. On the upper floor, you can activate gas dispersal, but the Rebreather Augmentation is highly advised. There is also a security hub surrounded by lasers. Triggering or destroying the lasers will activate turrets which will shoot at you. If you can get through them, you can hack the computer and turn the turrets against Fedorova. There are several ways through the lasers: you can use the stun gun to temporarily disable one laser, you can just walk through them using the Cloaking Augmentation, you can hack the nearby panel and turn off the laser, or you can break the wall near the panel and turn off the breaker powering the lasers. Note that triggering the lasers yourself, whether or not the turrets are fighting for you, counts as triggering an alarm and as such will void Foxiest of the Hounds. The turrets themselves are very powerful and can take Fedorova down after a few seconds of sustained fire. If you stun Fedorova with a stun gun while the turrets are shooting her, it's basically a guaranteed victory even on the hardest difficulty.

Glitches

 * Not necessarily a glitch as such, but likely unintentional behavior: Before summoning the funicular, if the appropriate augmentation is active, it is possible to effectively seal off the room by blocking the doorways with the turret, boxes and the vending machine. That way the enemies won't find a way into the room.
 * Fedorova will occasionally become stuck running in place.
 * Occasionally a bug can happen when you reach the end quest and try to go on the Helipad before Malik lands. When Malik lands and you tell her that you are ready it will end the quest but won't take you to the next level. Be sure that you save just after you defeat the boss and make sure you're not on the Helipad when Malik is landing to avoid this bug.

Trivia
The room names "802-11" and "404" in this mission are computer references:


 * "" is a set of Wi-Fi protocols developed by the IEEE committe.
 * "" is an HTTP error code that means "not found". This alludes to the fact that that Eliza is not actually in that room.