All you need is the Nightrunners-Vision-Potion. After you have access to the Central-Loop and Harper at the fisheye canteen you have to do some bounties for him to level up. When you reached Harper's Rank 15 just go to his shop and buy the Nightrunners-Vision-Potion-Blueprint for 3 tokens and 2000 mutation samples. Max it out and it will give you for 60 seconds a night view in the darkest spots.




Perfect to sneak in dark hollows or in the subway stations like during the "Spy-Game" quest.

Then you should read my other guide first:
https://steamproxy.net/sharedfiles/filedetails/?id=3120803030

https://steamproxy.net/sharedfiles/filedetails/?id=2994543199

https://steamproxy.net/sharedfiles/filedetails/?id=3030745696 part two:
https://steamproxy.net/sharedfiles/filedetails/?id=3031829467 and three: https://steamproxy.net/sharedfiles/filedetails/?id=3045159095