The Fourfold Mountain Lock

You enter a circular chamber carved into the mountain's heart. Four sealed stone gates block the far passage, each fitted with four dull metal plates. A waist-high slate console stands in the center, its four rotating drums clicking softly in the cold. Pale blue light travels through channels in the floor whenever a drum turns. Around you, loose grit trembles, a thin draft curls from one crack, an old coal smolders in another, and frost creeps across the last. Above the console, a damaged relief shows a mountain, wind, flame, and snow.