Unlocks: 'Vengeful Strike' achievement, 'Prisoner X' main mission
Approaching the Lair
Whichever direction you approach the Lair, expect a little resistance outside from a couple of guards. As you come inside - before you make the usual leap up to the passage above and the Lair proper - is a handful of guards and drones.
There's a panel in the middle of the room to disable the latter, but feel free to ignore it all and head straight up to the Lair, sprinting past the drone in the corridor and up, where you'll run to the corner, pull down some boards with your MAGrope, and head out to the antenna.
Eliminating the K-Sec presence and disabling the antenna
First things first, you'll want to disable all the drones here. Facing out from the window, they're all on your left side; one directly below, one up the higher area, and one in the left corner along the wall. Run from each and use the panels to disable them, otherwise they'll cause you hassle when fighting the KrugerSec goons.
Interestingly, whether by design or a bug, these drones remained disabled after dying and restarting this section, so it's worth doing them straight away even if you take a bit of a beating.
Defeat all the guards - as usual, use the various heights of this area to your advantage to chain from one to the next - and run to the antenna at the far end to 'start' the mission proper.
Once you've disabled the antenna, you have a standard alert phase to escape from. As always, the easiest way is to run to a safe house. We found Centurion Yards to be the nearest and easiest to reach, so set that as a way point, escape the Lair the same way you came in - avoiding the added goons that have spawned along the way - and keep up the pace until you get there. Mission done.