Hardcore Gamer
Ultra rare0.9%ObjectiveMissablePreviously-glitched
Complete all Operations on Difficulty Level 7+.
Mission replay is unlocked after completing the story, so you can go back and redo any you did on a lower difficulty. Agent unlock missions don't count. The original glitch was that if you didn't get this on your first run through of the game, it was impossible to unlock with mission replay. But this is fixed since early Nov 2017.