The Echoing Prisms of Galdur

Deep within the moisture-slicked cavern, four crystalline pillars of varying hues stand in a semi-circle around a central limestone basin. The air hums with a low, resonant vibration that tickles the teeth, and blue phosphorescent lichen clings to the walls like frozen stars. Each pillar emits a soft, pulsing light that intensifies when touched, casting long shadows across a series of weather-worn inscriptions carved into the cavern floor. A heavy stone slab blocks the only exit, inscribed with four empty circular indentations that match the shape of the crystals.