How to defeat boss Eliza Cassan in Deus Ex: Human Revolution?

It is not Eliza Cassan, but that girl with the weird hair that has the cloak that comes up right after seeing Eliza Cassan. I tried 10 times before going down to easy, and it's still hard. I have put emp grenades by the generators to bring her health down, then shot around 100 heavy rifle bullets at her, and she hasn't died yet. How do I beat her?How to defeat boss Eliza Cassan in Deus Ex: Human Revolution?
n deus ex human revolution, Eliza Cassan will "whisper" in Jensen's ears about how to defeat Yelena Fedorova. It took a while to understand her rumblings. In the meantime, let's reflect on Yelena Fedorova. She is the second-in-command to Namir in the attacks on Sarif Industries. To understand her tactics will allow Jensen to defeat her.



Yelena Fedorova will cloak, and make herself invisible. The only way to tell where she is in the near white room is to be close to her. To be close to Yelena Fedorova is too dangerous, as her melee attack will take Jensen down straight away. Alternatively, one could look at the water on the floor of the room to determine if Yelena is advancing towards you. However, she is moving too fast, and it's too hard to avoid her melee, charge and shotgun attacks when she is too close. One suggested way is to look at the radar instead, and see when Yelena turns into an orange arrow on the radar, and prepare Jensen's own assault when she is about to get close.



The options for Jensen's assault include cloaking too, and then attacking Yelena when she can be seen. Press Q and realize the failure of this method, as Yelena will counteract Jensen's sneak attack. Next, one can use the shotgun approach to attack Yelena when she is uncloaked and Jensen is cloaked. However, it does not appear to work. Maybe Yelena's skin and defense augmentation is too strong.



This is when Eliza Cassan's words start to make sense. She is saying that Yelena has the typhoon weapon upgrade made by Sarif Industries. She is also saying that destroying the power generators will temporarily hamper Yelena. Put the two together, and that means that Jensen need to use his Typhoon weapon upgrade. Head to one of the power generators, and position Jensen so that his back is against the power generators. Wait for the Eliza Cassan's warning that Yelena is close by and see this as the orange arrow on the radar. Next prepare to unleash Jensen's typhoon weapon as she is getting really close to damage the power generator. When the power generator is damaged and starts unleashing electricity (Jensen is damaged too), Yelena is stunned. Use the shotgun attack to attack Yelena. Repeat this as necessary depending on the difficulty level of the game. Finally Yelena Fedorova is defeated, and Jensen obtains the Mantis Achievement.



Eliza Cassan then spills the beans about the Sarif Industries attack, saying Sarif knows some of the truth about the attacks. Collect all the loot from this area, and then head to the helijet and back to Sarif Industries to talk to Sarif.How to defeat boss Eliza Cassan in Deus Ex: Human Revolution?
You can kill Yelena in about 10 seconds easily on any difficulty, if you have the Typhoon. Right at the start she will rush you. Use the Typhoon before she does, and she'll be stunned. Typhoon again (shoot her a few times if needed) and she'll go down.

The Heavy Rifle strangely isn't really effective against her. The Combat Rifle (or shotgun, or revolver with explosive rounds, or rocket launcher if you have it) works better. At least for me, because I have them heavily modified. Plus it has less recoil, no spin up, and no overheat.

If you have a taser, you can keep her stunned throughout the entire battle.

You don't need to use EMP grenades, they're more useful against Barrett. You can stay at the edge of the room and just shoot the generator boxes as Yelena rushes you. You can see the outline of her body even if she's cloaked, or listen for Eliza to warn you, or look at the liquid ripples on the floor as she runs. The electrcity will stun and fry her. But it's better to have the electricity immunity augmentation too. Shoot her when she's stunned.