I don’t see any official announcements, and I’ve been getting Epic Quest Chests from dungeons, so I’d like to know if anyone knows a list of dungeons that drop these chests?
See this page. The dungeons that drop chests are any which can have a grade B or better. And the chest dropped seems to match the chest you get with marks from that dungeon. I don’t know how it works for dungeons without marks.
Though beware that Deca are planning to nerf the chance to 1/3.