The Fortress Of Darkness — Patricia Perry

The elf prince Danyl vanquished the demon Mahn with the elven magic, the Green Might, more than two hundred fifty years ago, but that did not destroy the demon's black power. The sole surviving Vox, named Emhella, collects the scattered remnants of Mahn's dark force while the Races, once united, pay little heed to one another. Emhella combines his own brand of evil energy with Mahn's black magic, thereby becoming even more formidable than his predecessor was. All he needs to become invincible are the three most potent powers in the land plus the Riannian, the original magic from which all others originated. Transported over the massive mountains in the north by wraiths, a group of unsuspecting mortals is burdened with the immense responsibility of saving the land. The Keeper of the Elements, a dragon born with the land, gives them an ambiguous command: search for the other powers and for Varek-Tor, the fortress of darkness.