The KGB headquarters in Call of Duty: Black Ops Cold War is a small playground of deception and trickery in the Desperate Measures story mission. You as Soviet double agent Belikov need to obtain a keycard to let Adler and Bell inside, and General Charkov is the prime candidate to be your fall guy. You can frame Charkov, get a prisoner to kill him, or even bypass Charkov entirely. If you want a decent challenge, you can poison Charkov for his keycard.
You’ll have to go into dangerous territory in order to nab some poison for your devious plot. Go to the east side of the headquarters building and find a staircase to go down. Lockpick the door to enter the restricted area, and Kravchenko’s office will be ahead of you. Before you try to enter and lockpick the door to that office, keep in mind that there’s a guard on patrol to the left of the office, right outside the server room. It’s best to take him down first.
In Kravchenko’s office, you’ll see a convenient poison locker in the corner, with a periodic table of elements to the right of it. On Kravchenko’s desk is his computer; log into his computer, as you’ll find the lock combination here. Ignore the Access Mole Investigation option here, as you can’t do anything about that. Instead, look at the logs regarding Nova 6 — if you recall, this is the poisonous gas from the first Black Ops game. In the first log entry, you’ll see that the elemental and chemical composition of Nova 6 is Sulfur (S), Rhenium (Re), and Neodymium (Nd).
Check the periodic table and see where those elements are, and their atomic numbers will be your lock combination: 16-75-60. The Nova-6 poison is yours.
Sneak back upstairs and head to the northwest corner of the building. Speak to the guard stationed at the desk outside Charkov’s office. Say through dialogue options that you wish to speak to Charkov, and a [Poison] option will appear. Select that and the guard will escort you into Charkov’s office.
Take a seat as Charkov speaks on the phone, and the guard will serve both of you a drink. You’ll have the option to poison either cup, but because this has to be suspenseful, Charkov will turn around and grab the wrong cup. You’ll have to prompt him to turn around and mouth off about the good old times or his wife, during which you’ll have the opportunity to switch the cups. Prompt him to drink up, and enjoy the rest of this grisly scene that you’ve orchestrated.