Ambush

Fang has received intel on a squad of fully cloaked Monolith troopers working on an isomorph-powered explosive device in the depths of X-10 laboratory. They arrive into the lab every day, and open a mysterious code-locked door.
Fang's plan is for you to use the Cloaking exoskeleton and ambush the Monolith group, eliminating them once they open it.
==Walkthrough==
=== Preparation ===
Obtain a Cloaking exoskeleton with a High-capacity battery (the yellow one) for it. You can obtain both from:
* Controller's brains quest from Lukash;
* Safe in the cabin of the giant excavator in the main dome of the Pripyat Dungeons.
The cloaking mode needs to be activated by a hotkey you can bind in the game settings, check it out ("Suit ability", the same key to activate the SKAT-15). One battery is enough to power 2 minutes of full invisibility from everyone except BTRs, helicopters, and turrets. Your footsteps and other actions can still be heard.
Head over to X-10, and make your way to the Brain Scorcher switch room. You don't need to worry about sneaking just yet since the quest will only begin when you get into position.
=== Ambush ===
Upon reaching the end of the lab, put the cloaking exosuit on, and stand next to the Sarcophagus transition. Don't turn the invisibility on just yet!
You'll be rooted to the spot and Fang will contact you shortly. The group is closing in, but surprisingly they seem not to be Monolithians. A neutral stalker carrying a radio is among them. Fang will instruct you to leave him alive while killing the rest.
Nine invisible troopers will enter with Korn, a neutral stalker. Switch your cloaking exo on! If you are spotted or kill anybody before the door is open, you'll fail the mission. Radioman's rescue will start automatically. Korn will go ahead of the group and unlock the door while the cloaked troopers stand guard.
Once Korn unlocks the door, you will be free to move. While you still have charge in your battery to provide you with invisibility, move into a favorable spot like the entrance tunnel to the room. Switch to your standard armor, enabling weapon usage, and kill the troopers. Make sure not to kill Korn; once the firefight starts, he'll put his hands in the air and surrender to you.
=== Obtaining the information ===
After eliminating the invisible troopers, speak to Korn. The group appears to be from the mysterious Last Day faction that disappeared long ago. You've already seen some of their members - Sondr who cooperated with Gavr in the attempt to take over the Monolith, and also Beast and Squint, who led the group hunting Ghost.
Korn does not appear to be with Last Day; he's a business partner of Maximilian, and they had a base in the Central Pripyat kindergarten. Together they've been selling isomorphs to Last Day. The group didn't seem to have any issues with money, and also appeared to be carrying heavy bomb casings back and forth. Korn also tells you that the Last Day group fractured after a neutral stalker killed their leader (likely referring to Ghost's assassination of Henry) before uniting again under a new leader.
He also says that Last Day were also keeping a weird isomorph camera behind the door. The camera is only one part of the three; another part is the lens, which belongs to Maximilian and Korn, and is located at their base at kindergarten. The third part is the film, the whereabouts of which are unknown.
Behind the door, you find the isomorph camera, two bomb casings, and the information sheet with Last Day plans. They intend to find other parts for the camera, and infiltrate all stalker groups in the Zone to spy on them.
After this, Fang will enter the room. Speak to him and head to the kindergarten in Radioman's stash.
==Notes==
* The Cloaking exoskeleton has no carry weight bonus. Leave behind anything you don't need for the fight in a vanilla stash or rucksack just out of reach and retrieve it afterwards.
* The bomb casings aren't required for anything and you can leave them behind the door as Fang advises.
* In 40 seconds after triggering Radioman's stash, one each of the following artifacts in your inventory will transmute into the Spiral isomorph, similar to one you obtained in Artifacts for Klyonov. If you want more of them for any reason (for example you'll need one in Components search: 1st part), you can bring any of those artifacts. Any duplicates of these artifacts will be unaffected.
** Hide
** Tears Of the Electra
** Porcupine
** Steel Kolobok
** Fiery Dummy
** Drops of the Soul
** Plasma Caterpillar
==Bugs==
* The Last Day group could get stuck in the entrance tunnel due to tripping over a body, or just because they like it that way.
* Occasionally, Fang will spawn halfway through the fight and take care of the rest of the invisible Last Day members.