The Moonlit Courtesy

You enter a circular chamber of white roots and polished green stone. Blue moonlight pours through no visible window, illuminating four crescent-shaped recesses around a low altar. An owl hoots somewhere inside the walls, followed by a laugh that sounds almost like one of your own. A silver bowl holds black, motionless water, while a veiled mirror smiles before you do. Nearby, a music box clicks through three notes and stops at an empty fourth socket. Pale mushrooms pulse around the room, their silver lettering brightening whenever anyone speaks.