Tephra

Tephra is a human wizard. Formerly a heroic adventurer, she joined the mysterious Allabar after succumbing to her desire for power and opening a planar gateway to the Far Realm.

Hero
She trained herself from an early age and, seeking more power, applied to join the Starfire Academy in Silverstone. When she was rejected, she journeyed to Brightstone to look for adventures that could get her the power she so desired. Joining with Nuraya, Ro, Gryff, and Harthur, she investigated the disappearance of a powerful wizard over seven hundred years ago, eventually coming into the possession of a tome covered with faces that constantly stretched and moaned.

Tephra was transported to Estorium along with the rest of her party, and was eventually tasked with finding and stopping a mind flayer who was attempting to open a gateway to the Far Realm. They delved deep into the old temple of Boccob within the ancient city of Derenath, located the gateway, and slew the mind flayer. However, instead of closing the gateway, Tephra opened it fully, claiming the power within and allowing the nightmarish hordes of the Far Realm access to the world. She was last seen surrounded by aberrations, attempting to control them as her former party members fled.

Servant of the Far Realm
Through the portal, Tephra was contacted by a being known as Allabar. Through this entity, she gained incredible power and readily agreed to help him come to Syra. Though the portal was sealed by the now-mortal Boccob shortly thereafter, Tephra managed to defeat him with her new power. She forcibly extracted vast amounts of knowledge from his mind, including the method by which he had sealed the portal: an artifact called the Tear of Boccob. Knowing that the Tear could reopen the portal as it had closed it, she hired a band of mercenaries to locate it.

Herald of Allabar
Tephra was later encountered by the Challengers of the Unspeakable along Duvik Pass, attempting to open the prison containing the primordial Hoshotath. She told them that she now served Allabar, who had given her the ultimate power she had always dreamed of, and who would soon remake the world in his image. Hoshotath would destroy the world's defenders, paving the way for Allabar's arrival. She was defeated by Kalth, but her body erupted into a mass of writhing tentacles, and her telepathic voice told the Challengers that they would see her again.

Harbinger of Chaos
Tephra's next encounter with the Challengers was after they emerged from the Tomb of Horrors with the soul gems of Acererak. She asked for gems, and when they refused she summoned foulspawn and attacked them, but fled when the battle began turning against her. She met the Challengers again, further up the path, and when they again denied her request she summoned more foulspawn and attacked once more, teleporting away again when they began to gain the upper hand. She met them a final time only a few miles outside Silverstone; this time she did not fight them personally, instead summoning the aberration Shoth-Gorag to kill them before teleporting away.

Chosen of Allabar
By this time, Tephra had amassed a small army of fanatical followers, and made her base within the ancient Fortress at World's End. She also made contact with the demon lord Orcus, promising him the Scythe of Nerull in exchange for his help. She also began making plans for an assault on Silverstone. Her minions soon delivered the Tear to her at the Fortress; she used it to open a small, unstable portal to the Far Realm and focus the Tear's magic through it. As the Tear was linked to the dormant portal in Estorium, planar energies from the Far Realm had been steadily leaking through it, and by focusing it back through the Far Realm it would cause the seal on the portal to unravel.

The Challengers interrupted her in the middle of the ritual, however, and after a long battle Tephra escaped through the portal into the Far Realm shortly before Kalth threw the Tear into it. The planar energies of the Far Realm spilling through the Tear into itself caused a feedback loop that destroyed the Tear and collapsed the portal, but Gryff was sucked in and lost.