In order to obtain Self-Reflection, you must pick up the Case File: Mirror Supplement collectible found near Logistics and Security.
Locate the Mirror in Synchronicity
If you haven't discovered Synchronicity yet, fast travel to Ritual Division in Maintenance, then leave through the north-west door marked Synchronicity Lab. Follow the signs to Mirror Testing on the right-hand side of the main room, then use your level six clearance to get through the next door.
Find a way into the Containment Cell
To get into the Containment Cell, you need to solve a puzzle. If you want to do it yourself, use the security cameras to see what order you need to open the shutters on either side. If you're not a fan of puzzles, here is the solution (also pictured below):
Left side (left to right)
Open, Open, Closed
Right side (left to right)
Open, Closed, Closed
This will open the main door so you can go inside and interact with the mirror.
Explore the reflected space inside the Mirror
Go inside the mirror, leave through the double doors, then start interacting with the different cells in the Synchronicity Lab. Eventually, the Essej boss fight will start. She's slightly tougher than most other boss fights in the game, but she doesn't do anything particularly special other than use your own abilities against you. The difficulty mainly comes because she has a lot of health, so keep shooting and using Launch to throw stuff at her and eventually she'll go down. Head back into the Mirror Lab and interact with the mirror to cleanse it.
Main Missions:
Control walkthrough: Welcome to the Oldest House
Control walkthrough: Unknown Caller
Control walkthrough: Directorial Override
Control walkthrough: Old Boys' Club
Control walkthrough: Threshold
Control walkthrough: My Brother's Keeper
Control walkthrough: The Face of the Enemy
Control walkthrough: Finnish Tango
Control walkthrough: Polaris
Control walkthrough: Take Control
Side Missions:
Control walkthrough: Old Friends
Control walkthrough: Fridge Duty
Control walkthrough: Self-Reflection
Control walkthrough: Mr Tommasi
Control walkthrough: Old Growth
Control walkthrough: A Matter of Time
Control walkthrough: Langston's Runaways
Control walkthrough: The Enemy Within
Control walkthrough: Mold Removal
Control walkthrough: What a Mess (all missions)
