Xem'Zund
Xem'Zund was one of the most powerful necromancers to have ever lived, and perhaps the only true archlich to ever exert his power on Althanas. Like the other Forgotten Ones, Xem'Zund's immense power stemmed from his mastery of the raw and infinite magical energy source known as the Eternal Tap, the knowledge of which has greatly waned since the War of the Tap.
Xem'Zund has long been a primary enemy of Raiaera and its elven people, having assaulted them several times over the centuries with undead hordes. Most of these assaults were easily thrown back, as the elves had fortresses designed specifically for this purpose: Carnelost, for example, was a watch-city erected at the foot of Lindequalmë, the Red Forest from which Xem'Zund's assaults all originated, and until recent times Carnelost was almost unbeaten by the necromancer's undead forces.
Xem'Zund's most successful attempt at invasion came in approx. CP1799, following a failed invasion attempt by the armies of Alerar. When the dark elven general was killed by Devon dan Sabriel at Valinatal, their host was turned back as all previous attempts at invasion had been. But Xem'Zund struck while the opportunity was ripe, with one of his greatest assaults yet. A jet-black mimic of the Glass Palace in Eluriand--the Obsidian Spire--sprang up out of nowhere in the depths of Lindequalmë, tall enough to be seen from Eluriand itself, and his mighty Corpse Horde found the Carnelost mostly abandoned, its warriors gone off to join the defense at Valinatal. Carnelost quickly fell.
The ensuing conflict, in which much of Raiaera was destroyed including its largest cities, was known as the Corpse War, and it paved the way for the Great Invasion of Alerar.
Just as Devon once vanquished him in a previous invasion, Xem'Zund was eventually defeated in the heart of his own Obsidian Spire by a band of heroes including Ingwe Helyanwe, Cydnar Yrene, Drusilia Liadon, Lillian Sesthal, Caden Law, and Godhand Striker. This time, however, the Forgotten One's demise is believed to be final, for the heroes managed to bring the power of the Eternal Tap itself to bear against the one who had been granted immortality through it.