From the introduction:
A 5th Edition Mini-Dungeon adventure for 4-6 PCs of Levels 11-12.
Deep below a mine and the natural chambers it connected to, a cavernous grotto steeped in ancient magic exists, a place where arcane forces attract spectacular beasts and cause constructs to spontaneously appear for short periods. The rocks pulse with indigo energy, while minerals suitable for rare weapons glow with turquoise, lime, cadmium, and other green shades. Such treasure attracts its own pioneers; a duergar mining caravan gathers material for its high priest’s next heavy mace.