The Laughing Root Door

The cavern air is cool, wet, and sweet with mushrooms, and the far wall is dominated by a round stone door banded in silver roots that seem grown rather than carved. Three concentric rings of glyphs turn within the lintel, each click sending a little ripple of colored light through the stone. When a ring is set wrong, the door exhales a tiny burst of glittering mist and a distant voice snickers from inside the rock; when a ring is set right, the carvings warm under the hand and the chamber hums like a tuning fork.