The Copper Tower

Publisher's blurb: A 2-4 hour stand-alone dungeon designed for a party of four 3rd-level adventurers. A mysterious tower made of copper stands in the clearing. An odd black form rests on the very top. You approach the tower, which upon closer inspection appears to be more of a giant copper cylinder rather than any tower you have seen before. Along ground level is a large oaken double-door. Pushing the door open, you are greeted by intense cold and darkness. The beam of light cutting into the darkness from where you open the door reveals a floor made from ice. Like a lake frozen over in the depths of winter.