The Crystalline Caverns

Publisher's blurb: Tucked away within this partially-eroded mountain lies a cavern, glowing with dappled rainbows. Light reflects off colorful crystals, some red, others blue, purple or yellow. They ring slightly, thrumming with some kind of innate power. The verdant green ferns and wildflowers stop before you reach the cavern. There are no signs of animals within, either, despite many habitable tunnels breaking away from the main cavern, and leading deeper into the mountain. To enter this hair-raising place, you must first cross a steep, rocky gorge. Beyond that wait the statues of robed figures, holding swords and guarding the entrance.