As with every feature of Stygia, and the other supernal realms in general, the nature of the Watchtower of the Lead Coin varies depending on who is observing it. It is generally agreed to be a great spire jutting up into the clouds, or a pyramid that would dwarf any ever found on Earth, after that the descriptions begin to vary. Many say the tower is built entirely of some heavy metal, usually lead or gold. Some have suggested it is in the form of an immense stack of bones, which a supplicant must climb. Other substances like white marble or black obsidian have been known to appear from time to time.
As the mage ascends the tower and passes through the clouds, the sunlight of Stygia grows brighter and brighter, creating the well-known 'tunnel of light' near-death sequence. At the top of the tower one must forge a connection to Stygia. This can be simply carving one's name into the tower with magic, making a blood offering, burning oneself on a funeral pyre, even forging a new Artifact to add to the treasures. Sometimes there is a gatekeeper, in the form of a Grim Reaper, a black cat, an executioner, or ghosts of the mage's relatives. At other times, the tower is abandoned.