Deceit 2

This one is rather grindy. In matches there are many, many tasks that you can do. Tuning radios, flushing toilets or matching cards as a few examples. Some tasks even require two players. After light interactions often taking like ten seconds or so the bottom of the screen will say "task complete" and your wrist will get more magic essence. You need to do this 1000 times.

I've been able to get at least 10 tasks a game done, usually more by just running about interacting as they're a fundamental part of the game. That hopefully gives you an idea of the time commitment.

Update: As "Ghugh" mentioned you can indeed track it. Go to "Ascension", tab down to "Maps" and "On the Job" is the circle you're looking for to hit Diamond level. That should help.

Update 2: It's somewhat buggy. Others have mentioned getting it over 400 tasks into the Diamond level "On the Job" ascension tracker. I got mine at 438 and it popped mid-match.