Genevieve Gruyère Achievement in Vampire Survivors

Before you can do this achievement, you'll first need to unlock the stage Abyss Foscari (refer to Abyss Foscari (5G)), and then you'll also need to break the Seal of the Abyss (refer to Luminaire Foscari (5G)). With those done, start up a run on Abyss Foscari with Eleanor. You'll need to evolve her starting weapon (refer to the roadmap or Ophion (5G) if you need a reminder how) and head to the question mark on your map (it's a new one). To get to it, take the same route as the previous Seal (head directly south from the spawn until the second opportunity to go west, past the waterfalls). When you get to where the previous Seal was, continue west as far as you can, until you're essentially directly south of the question mark. Now you can head straight north to reach it.

You'll need to hang out near it for a little while until your weapon finally breaks it. This achievement will unlock immediately, and it'll throw you right into a boss fight against Je-Ne-Viv. Refer to Hyper Abyss Foscari (5G) for tips on this boss fight.