Mystara: The Penhaligon Triology, Book 03 - The Fall of Magic

A sinister mage has unleashed the power of an ancient artifact on the land, an artifact that drains the world of magic. Worse yet, the evil armies that pour through the artifact may bring about the end of the Castle of the Three Suns. In a final, desperate gambit to turn back the tide of doom, the Penhaligon knights ride far and wide to defend all of Mystara from this magic menace. Meanwhile, Johauna Menhir sets out on an impossible quest to foil the malevolent mage. She seeks to enter the artifact and, with her immortal-forged sword Peace, slay the wizard Auroch.