Thanos the Eternal
Thanos the Eternal, named after the ancient Sejannese word for death, was a lich who hunted down the Heroes of Crucibal.
He originally was a high elf named Thanistys Nightcandle and an Enchanter. He joined a group of like-minded mages called The Sanguine Circle. They were trying to wrest control of Sejanna away from the Phyrexians during the Purge and then rule it for themselves. The head of this group was Rhadamanthus, a human archmage. Rhadamanthus knew the secret ritual to banish the Phyrexians back to their home plane, so he convened the Circle together and performed the ritual.
Legends differ as to how many were in this group, some say eight, others twelve, but during the ritual something went wrong and the lifeforces of all the mages were snuffed out one by one in series except for one: Thanistys Nightcandle. He absorbed all their energies and shed his mortal skin. He became an undead lich – Thanos the Eternal. He found the Forgotten City of Lor Susshro, once an old Iparian colony, and took control of its underwarrens. From there he plotted and planned to rid the world of the Phyrexians. Just as his plans reached fruition, a band of heroes from The Vale used the Staff of Law and remade the world, thus banishing the Phyrexians forever. To those heroes went all the recognition and glory.
But Thanos would have none of this. He plotted vengeance and sought out the likes of Ulrich Ildrae and his cohorts to hunt down these so-called heroes and slay them. The plan backfired and instead they, in turn, were slain or scattered and brought the attention of the heroes to Thanos.
In their first epic battle, the heroes were bested (a certain dwarf forgot he had Blind-Sight) and Thanos claimed victory and started enchanting the Mindstones and sending them to the scattered new rulers of Sejanna in order to entrance them into his power.
However, the heroes regrouped and came at him again in the very same place: Lor Susshro. This time the heroes were successful. They forgot to destroy his phylactery, however, and Thanos returned several days later.
But this time, when Thanos used his magic scrying mirror, another spirit took it over. A dragon named Melmoth who also demanded revenge against the heroes. In a moment of weakness, Melmoth invaded Thanos’ form and assumed his second incarnation. In so doing, his skeletal frame became steel instead of bone and he waited for the final showdown.
During the last battle, Thanos had trapped Skylurk Fei in a magic jar (a gem actually). He had done this to a Justicar named Alaric some time before and slew him thereby. The heroes had to rescue Skylurk before it was too late, so Thanos had a chip to use against the heroes and a means of forcing their hand.
In the final confrontation, the heroes decimated Thanos and found his phylactery and destroyed it in flame. Skylurk Fei was rescued and they took over Lor Susshro as their desmesne. This later transferred to Grable Pando as fief and then finally as Lor Pando after his ascension to godhood.