This is one of three missions available to you at one time. Note that after finishing two of these, the simulation will be overrun by a lot of gang members, so it would be wise to do the A Game of Clones to get rid of them.
The simulation this time is going to be Asha’s, which will play out like a stealth game. When you gain control, go to the first door and wait for Asha to open it. In this first corridor, Asha will tell you to shoot out the lights and then continue past the door, making sure to stay out of the light after that as you sneak by the other guard in the room.
Instead of sneaking by the guard after that, you’ll shoot out the light and then have to perform a stealth kill. For the next guard, things will be done a little differently, as instead of shooting the light, you’ll need to go into the vent nearby, which will bring you within range of the light you need to shoot.
The next spot mixes things up a little more (along with a Metal Gear Solid reference, which this whole mission really is), as you have two lights to shoot and two guards to kill. It’s a lot easier to get headshots on the enemies instead of doing stealth melee kills.
After Asha opens the next door, you’ll be in an area with more guards, but there’s no lights to shoot this time. As you approach the marker, both you and Asha will don some cardboard boxes and use them as cover. You have to sneak up on the enemies patrolling the room and perform a stealth, with the first guard being stationary and the other two moving.
Keep going through this area until you come to a wall of lasers, which Asha will want to go through, but your character says they will use the conveniently placed air duct next to it. After going through it, watch the cutscene and then go through the next areas, killing the enemies that get in your way. Once you get to a big room, kill the rest of the enemies and the battle with Mr. X will start.
The evil version of you has a sniper rifle and will stay on the ledge above you. Throughout the fight, more henchmen will appear, with Murderbots also joining in the fun later on, so be on the lookout for those. Keep shooting at Mr. X until your evil twin activates the generators nearby. The boss will do this to regenerate their health and you need to shoot one of the generators until they shut down. The whole fight will be this pattern until you deplete Mr. X’s health, ending the mission.