*This guide will be written under the condition of:*
Difficulty: Amateur
Start Ada's Chapter 4-2, which will take you to the Bridge. Scale up to the door and open it to start this whole sequence. You'll know it started when Chris/Piers ride the elevator up and spot you. From closing the door, dash into the next room to avoid being locked in and go up the stairs. At this point, interact with the window to see the large room with a platoon of J'avo soldiers. Then exit the nearest doorway to the outside, where you'll be introduced to the spotlights.
When you regain control, hold
and run around the walkway to the next grappling point. Here, you can find one of the Serpent Emblems for this chapter by turning slightly behind you and aiming at it while still outside on the porch-like setting. Once you've acquired that, run in, hop into the vent, and climb your way through while listening/watching to the other team clear the room beneath you. On the other side of the vent, you'll have a linear path that intersects a side room with another J'avo; avoid them, or take them out silently. Either way, you'll proceed further and come to a control room with a pacing Gnezdo (the wasp and body of flies).
I'm not sure why, but the PS4 version was walking incredibly fast.Wait for the figure to walk past, then keep your distance following behind it slowly. Near the button, it might start to do a bit of a crazy path before it resumes, but this part and the part after might be the hardest to avoid being seen in. There was a checkpoint prior to reaching the control room, and one after; if you press the button and get seen before passing the doorway, you will have to restart your efforts from the beginning of the suggestion rather than by simply restarting the checkpoint. Clear the button, reach the next checkpoint, and then drop down for more spotlights.
If you can, try to run towards the opening near the walkway and press
to start crawling. This should be within enough time to avoid the spotlight seeing you. Wait for it to go past you and then crawl to the halfway point in the walkway. Let it wave past you going back to where it started and then scramble off the walkway and back into a walking/running stance. Run while holding
to get to the next grappling point without being seen, and you'll be near the end of this gauntlet.
At the top of the grappling point, ready your weapon and use the nearby wall to Cover up to the edge. Aim for a headshot to clear the enemy away, and then freely run up the ladder. Continue until you reach another vent, but once you crouch down, ready your weapon for the patrolling enemies within the vents. If you can, try to take each of them out separately by aiming for their human body/head. Do not allow them to witness you or one another dying, or this might void the trophy and require you to restart (though perhaps restarting via checkpoint might still be doable at this point). Clear both, exit the vent, watch the cutscenes, and you've got one stretch left.
You can view Carla's corpse from the perch you appear on once the cutscene is done (not sure if that matters), but continue on until you make it to a drop-down point. From here, hold and press yourself against the left wall if possible. There is one J'avo left and they will be pacing the hall near the elevator. Wait for them to turn around to either run up and sneak attack it with
or just finish it with a crossbow bolt. Either way, enter the elevator, exit at the base level and claim your weapon if you haven't, and I'd say start the cutscene with inspecting Carla's body.
For me, the trophy didn't unlock until I loaded in after the Carla cutscene. For another, it unlocked shortly after riding the elevator. It's easier to just wait longer at the drop-down point after loading into the next scene of this chapter. Hope this text guide helps others.