You deactivated at least 5 security systems on Kingsparrow Island
During Mission 9: The Light at the End, you will have to deactivate—through the use of a Rewire Tool or removing the Whale Oil Drum from the power source—at least 5 out of the 6 possible security systems found on the island. They are, in the order that you can discover them:
Watchtower - the large, grey, rotating tower that has a spotlight on it at the very start of the mission. It is only accessible with Blink level 2. If you do not have it or enough Runes to unlock it, simply ignore it and disable the other 5 systems.
Arc Pylon #1 - small pillar that electrocutes those that come near it, located to the very right the starting mission area.
Wall of Light x 2 - two electrified gate areas that block your passage on the left/right sides. To gain access to them, go near the left wall of light and follow the wall just to the right of it. You will see an open storm drain that you can blink onto. After entering it climb up into the room, where there will be a Whale Oil drum to the left and right.
Arc Pylon #2 - after gaining access to the compound you will eventually make your way up a long, winding flight of stairs. At the top you will cross a walkway that has an Arc Pylon on it and several enemies.
Gears - the sixth and final defense system is misleading, since it is not only a unique defense system to this level, but it is also in the second area of the mission. At the very end of the mission you will be standing in front of a machine gear that you must deactivate to proceed. If you skipped the watchtower, this will be the 5th deactivated system and the trophy will unlock shortly after removing the drum.
To see a complete walkthrough of the first 5 defense systems, please refer to the video below. Remember that the sixth and final defense system is impossible to miss if you finish the level, so you do not have to deactivate the Watchtower to get this trophy. Which is impossible to do if you do not have Blink level 2.
To see a walkthrough of the first 5 defense systems, please see the video below:
You've written a good guide, but with all due respect, its easy to get on the watchtower with blink 1. Maybe it was fixed in a patch. Just stand at top of the rocks from the stairs, point your reticle at the spot just above where the plank will stick out when the turret rotates, hold L1 for blink, and jump up & forward when the plank is just under your target reticle. At the top of your jump, release L1 & you'll climb right up it, no prob. I got it first attempt.
The gear is not required. You can use blink to climb the supports around the elevator, which puts you on the roof and allows you to enter the lighthouse through the back door.
In fact you can skip all of the security systems. Just use blink II to get on top of the rock with the wire running to the fort that is farther away than the starting point. Just swim up to it, aim blink at it until you see a spot that shows the icon for climbing up ledges, get to the wire (carefully) and run all the way to the fort. From there, use blink to get to the fortress wall, run along it, use blink again to get onto the opposite end of the barbed-wire covered line, then follow the wires all the way up to the elevator, being careful not to fall off.
Make sure you save frequently in case you mess up, and
I'm surprised that no one has mentioned yet that there was a third wall of light. Right after you enter the fort through either of the first two walls you can either go through the drainpipe or proceed through the gate, past a third wall of light, the whale oil tank and security panel are above it, in the rafters of the fort.