I'm really curious about this guy. He's the leader of what is, in a standard epic Good vs. Evil game, possibly the most influential Evil empire on Erebus second to the Infernals. The Sheiam have the most unusual method of acquiring an army in the game, building only a handful of units while their main forces pour through Planar Gates. If FfH were a CRPG, he'd be the main villain (or possibly just the guy who looks like the main villain before Hyborem comes in right before the boss fight and chops off his head, but that's still an important role). From what I've gathered from Kael's posts on the forums, he was an important character in the original DnD campaign. And yet his civilopedia entry looks more like a placeholder than anything else. All the official information we have on him (save the "Corruption of Spirit" quote) boild down to five sentences:

Once an Amurite archmage named Ran in the Age of Magic, Tebryn was caught in a battle between a thieves' and assassins' guild. Untended by his bodyguard, Ran was set upon by a viper assassin and killed. Hyborem personally collected his soul and introduced him to the glorious tortures of Hell.
After centuries of punishment, the goddess Ceridwen stole Ran's soul from hell and loosed it on the earth, renaming him Tebryn Arbandi and promising that he will no longer endure Hell if he causes the Armageddon. Now Tebryn is willing to do anything to save his soul, even if he has to damn the rest of the world to do it.

The first fact is particularly strange, since the Amurites are explicitly stated to "have no ancient history, no glorious empire in the Age of Magic to harken back to or trace their lineage from," but I'll assume that it just means he was part of Kylorin's empire. Still, his life before death is ultimately unimportant: As much as I'd like to know why the assassin's guild was targetting him or why they were at war with the theive's guild in the first place, I care less about Ran than about Tebryn Arbandi. Surely he can't have been the only archmage in the Age of Magic--an age noted for being filled with powerful, evil spellcasters--to die and go to Hell, so why did Ceridwen choose him over everyone else to bring on the Apocalypse? How did he meet up with Os-Gabella, and what sort of relationship do they have right now? Why have I heard that he cannot die until Abashi has been slain? What does he think of Cardith Lorda, who seems in many ways his dramatic foil? In short, who is Tebryn Arbandi?

Tebryn is a lich, and his soul is contained in a phylactery that Abashi carries around on his forehead (IIRC). Thus, one must first kill the dragon and get the phylactery before standing a chance before Tebryn.

Edit: beaten to it hehe

I believe both he and Ran were player characters in one Kael's D&D campaigns.

The first fact is particularly strange, since the Amurites are explicitly stated to "have no ancient history, no glorious empire in the Age of Magic to harken back to or trace their lineage from," but I'll assume that it just means he was part of Kylorin's empire.Yeah, in our revised history, that should say "Patrian", the original Kylorin empire.

And yet his civilopedia entry looks more like a placeholder than anything else. All the official information we have on him (save the "Corruption of Spirit" quote) boild down to five sentences:Yeah that could use some work... hmmmm

Yeah, he is almost directly out of the D&D campaign as hasnt really been converted to FfH. He could use a once over, up for it Nikis-Knight?

I remember seeing a list of the original students of Kylorin; Perpentech, Os-Gabella, and the like. Was he one of them, or is he a later addition?

There is a full list in the pedia now. Giant entry on the History of Erebus has all 21 students of Kylorin, Archangels, Angels and some other 21 that I cannot recall presently I think.

He is not in the list (either as Tebryn or Ram)