Plasm: the shimmering substance that powers a world civilization

The tremendous mass of the world-city generated a mysterious substance - the plasm that accumulates like rising water under the concrete and steel. Latent unless tapped, plasm can propel ships or knock down buildings; it can reverse ageing, amplify sex or alter genes. its awesome geomantic power can penetrate anything-except the impermiable Shield the Ascended Ones placed between the world and the heavens, denying humanity even a glimps of the stars.