Glass Vizard Achievement in Vampire Survivors

This "relic" is located in Moongolow, the second bonus stage. Refer to Boss Rash (5G) for unlocking bonus stages.

Before you can get this relic, you'll need 8000 coins. You don't need to earn that much in a run, you just need that much available between runs. Once you have that much, start up Moongolow with any character, and you'll start right next to the Glass Vizard, who is the merchant. Touch him and then choose the top right option to allow him to show up in any stage, which costs 8000 coins. This unlocks this relic and this achievement.