From the back of the book: 'There are powers even greater than magic . . .' In the misty recesses of time, before the kingdoms and lands you know—before the elder elves, the dwarven ancestral lords, and even the dragons—civilizations undreamt of rose and fell. They built citadels of metal, glass, and light. They crafted wonders and harnessed energies we can only guess at. The remnants of their incredible creations now lay hidden away in the deepest recesses of the world. Those few learned folk who even know about them have a name for these places, objects, and even creatures. They call them the . . . 'Arcana of the Ancients' Since the very early days of tabletop RPGs, gamers have experimented with mixing a bit of science fiction into their fantasy. From Empire of the Petal Throne to Expedition to the Barrier Peaks, early adventurers into the realm of RPGs saw the amazing promise that mysterious and weird science-fantasy elements could add to their fantasy campaigns. Nowadays, who knows science-fantasy better than Monte Cook Games? Arcana of the Ancients brings the wonders of mysterious technology and weird science-fantasy elements to your fantasy campaigns. Designed by fantasy masters Monte Cook, Bruce R. Cordell, and Sean K. Reynolds, this gorgeously illustrated sourcebook gives you everything you need to add a whole new element to your Fifth Edition game. Arcana of the Ancients includes: Hundreds of cyphers, artifacts, and other items that incorporate science-fantasy technology. Over 50 science-fantasy creatures, each with awe-inspiring artwork and complete 5e stat blocks. Pages of GM advice and guidelines for adding science fantasy concepts to any existing fantasy campaign—or building a brand new science fantasy campaign from the ground up. The Hills of Crooked Sleep, a hefty adventure you can insert into your campaign right now to introduce ancient civilizations, weird technology, and new strange creatures. *Plus additional full-length adventures! An introduction by Jim Davis and Jonathan Pruitt of Web DM.