Note: This information was taken from TSR's original AD&D adventure, the Temple of Elemental Evil.
For the DM: Broad stairs lead down from the inner chamber into a round room 60 feet in diameter. A soft glow from the destination lights the stairway in an odd pearly glow mixed with occasional flashes of other colors.

The walls of the round chamber are vertical, 20 feet tall, capped by a dome reaching 10 feet further. In the center of the room is a round dais about 2 feet tall, which is precisely encircled by a column of shimmering light, the source of the radiant colors, which extends to the ceiling.

The walls and ceiling are ornately decorated by a mosaic mural, apparently made entirely of precious stones -- emeralds, rubies, onyx, and the like. Not a square inch is uncovered. The scene on the walls is one of glory and conquest, showing the lands around as seen from the parapets of the Temple itself. The countryside is somewhat warped (in an undefinable way) but easily recognizable, and is filled with beings -- human, humanoid, and monstrous mixed together -- all facing and paying homage to the Temple.

Intruders may pry out up to 65 gems with relative impunity, each worth 100-1000 gp. However, if and when a 66th gem is removed, the attention of luz is called to the chamber, and he arrives in 1-4 rounds, accompanied by 1-4 demons of types 1-4 (each variable checked by a separate roll), luz also comes if the area is damaged by fire or lightning, or possibly (80% chance) if his name is spoken aloud by anyone in the chamber.