Army of Ruin
221 Achievements
GOG
Obsidian Crown
Forge III - Upgrade Leather Bracer to Level 5
16.8%
How to unlock the Obsidian Crown achievement in Army of Ruin - Definitive Guide
Leather Bracer is one of the starting trinkets, so simply play until you get it to pop up as an option, then raise it to max level to unlock this. Eventually you'll unlock Favorites as the final feature in the game, and can use one on Leather Braces to ensure it shows up during a run.