The idea of long-lost cultures that were technologically or magically superior to those of the current era of a game setting is fairly common in both fantasy and science fiction.

This mini-sourcebook contains entries for two dozen sorts of materials that were developed by ancient societies but which can no longer be created without the assistance of powerful magic or technology. They are suitable for use in any fantasy, modern, science-fiction, or post-apocalyptic games that use the d20 system and can easily be adapted for other games altogether.