Styx: Master of Shadows

You actually get this for collecting all 8 RELICS, not the 100+ "treasures" of the game. A little confusing.

If you are going for 100% in this game, it's best to do all of your Insignia attempts together (stealth + no kill + no alert + speedrun) because you will need every single insignia skill point on top of every objective in order to just have enough points to buy all of the skills and get the last achievement. For that reason I do NOT recommend going for these on your first attempt. Much easier to kill everyone in sight and collect all tokens your first run then do a full insignia run right after while the level is fresh in your mind.