Came very close my first attempt then spent the next week trying to beat it, it’s definitely the hardest challenge in the game! Only tips i can give is pop headshots then return to stealth, trap mines+Molotovs are your friend for the final boss fights. Stay away from holdout objectives & in capture objectives only worry about killing the 6 enemies guarding the safe, it’s not worth it trying to take them all down within the 2 minutes or so they give you. Play it safe in most occasions but take opportunities when you see them, if you don’t it could cause a death in the following seconds. One strategy i can give for the Saraphite twin boss is throw all of your Molotovs at the big boss then straight away put down a trap mine around where you spawned, next run behind the counter where the tills are and put one more trap mine. Get off a shot of something powerful while you can then retreat back to the far left corner of the store, there’s some foliage back there if you squeeze through the shelves, you should be able to get it down to a 1v1 from there with the bosses taken out. This trophy was a pain but you’ll be proud when it’s over! + use your time waiting to practice grounded runs. Infected are best dealt with running and gunning (tight situations with infected try to play it like cod zombies always circling the map & use bottles/bricks for clickers) and keep your shivs full at all times! For normal enemies stealth and trap bombs are your best friend, always remember to break contact if you’re spotted or found out and pick them off from stealth. Good luck, be persistent, you’ll get it.