Miang Achievement in Vampire Survivors

Like all coffins, the coffin in Mt Moonspell is marked on your map as a big obvious question mark. Getting to it, however, is more annoying this time, as the northern part of the new map is, frankly, quite annoying to navigate. To get to the coffin, from your starting point, head just north a bit until the path splits into left, right, or straight up. Make a right to head over to an area with a giant building. You need to enter it on the south end and work your way through the mini maze upward to find the coffin in the center. I personally didn't see the usual ring of enemies come out of the coffin like in all normal stages, but just kill all the surrounding enemies in the area until the coffin opens when you walk over it, granting you a new character.