Well, everything got much more clear and complicated at the same time. Without the "clear" part...
So, we know that there was a corrupted great in ED - Vestrivian the Despoiler (voluntary possessed by a Horror in pursuit of learning ALL KINDS OF MAGIC).
But he flew to the Horror Cloud near Vivane
that was attracted by the ritual of Elemental Air dome
which had been adviced by Mountainshadow (Dunk) and held by Dvilgaynon (Tva-il-guya-noon, Burning Orchid, Sunset Blossom)
and vanished - presumably was killed as he didn't manage to stop the cloud.
But - Have no idea whether it is official info, or "funfiction". Got it from
https://earthdawn-the-age-of-legends.obsidi...haracters/28443"Many years later, when The Passion’s Champions were attempting to reclaim Bartertown from the Reavers, Vestrivian appeared again and offered Nazeer an unusual bargain: he would give them information on the Horror’s movements and intentions, using his in depth knowledge to aid them. In exchange, he asked that Nazeer end his life once the knowledge was used, as he was uniquely equipped to do so. Nazeer agreed, although Vestrivian warned him that he might receive false information from the Despoiler, and to be wary of all advice given."
But he (Vestrivian the Despoiler) might have been seen by some Boast-smthng in a Maya Storm (WHEN???).
By the way! I've found the following topic here, on Dumpshock:
http://forums.dumpshock.com/lofiversion/index.php/t5290.htmlQUOTE (Demonseed Elite @ Aug 28 2004, 05:05 PM)

Haven't seen a good ED/SR conspiracy thread here in awhile, and I love the conspiracy discussion, so here's a topic for talk: corrupted dragons in SR.
Besides the rumors of a corrupted dragon being involved in Aztechnology, which go back to the Aztlan sourcebook, what about other ideas to chew on?
What about the Children of the Dragon and the Children of the Dragon Reborn? I have to wonder if there's anything more behind these groups, including the possibility of something sinister. There isn't much to go on, but any cults of dragons always make the hairs on the back of my neck stick up when I read about the Cult of the Great Hunter in Earthdawn, which served the Horror Verjigorm. Verjigorm wanted to corrupt dragons, and collected both dragon eggs and dragons for that purpose. A cult to dragons would serve his needs, on the surface. However, there haven't been many links to support this in the Shadowrun books, that I can think of.
And what about Ghostwalker? He hasn't seemed to garner much suspicion from the other Greats, but his arrival was very suspicious on its own. If you read the journal entries from Hefara on pages 51-54 of Secret Societies of Barsaive, there's an account of a Verjigorm-corrupted dragon being visited through a rift to the astral, where it's astral form was cocooned and corrupted until being set free by the cultists. No one really knows where Ghostwalker was before he returned, but he did exit through an astral rift, and he did bring with him some "wormy" and "slimy" spirits who gave off a "bone-numbing 'I'm going to tear away your sanity' feel" (quotes from the Ghost Stories chapter of Year of the Comet). Some of them were likely shedim (which are suspicious enough on their own, especially if you read about the armies of undead in Barsaive in Chaos, which are actually puppets of a type of Horror), but who knows what else might have been among them? Doesn't really seem like Ghostwalker was in a happy part of the astral while he was away. So if he was in a bad place, gotta wonder why he was there, and what was going on all the time he was there.
The real question would be that if Ghostwalker were corrupted, why haven't the other dragons taken note of it? Or would they stop him? Afterall, in the Fourth World, Vestrivian was a Horror-marked dragon, and the Greats never banded together to destroy him.
The last interesting note is Calozerca, a newly released dragon near Poland that is mentioned in Dragons of the Sixth World. What's interesting about him, despite the fact that it seems like he was locked away for a reason, is how similar the entry on Calozerca's release is to the account found in the Cult of the Great Hunter entry in Secret Societies of Barsaive. In that entry, the Cultists use a staff to assist in freeing a corrupted dragon from one of Verjigorm's cocoons in the astral plane, and they open the astral rift to the cocoon in the Thunder Mountains (not far from the same mountains where Calozerca was released). In the entry on Calozerca, a staff is used in a ritual that is not observed, but shortly after Calozerca is terrorizing the countryside.
Makes one wonder!
The only thing i failed to get - whether Vestrivian was a Western or an Eastern Great. It might be important as we have a description of a corrupted dragon on the Tenachtitlan pyramid as an Eastern one.
But (again!) this one could be Great or not - just a corrupted dracoform, possibly by use of Blood Magic,
which Thais-Half-Horror could be the one to teach to the Azis right after teaching the ritual of the Great Ghost Dance to Coleman or Coyote.
Hew! That's the part i LOVE in role play games!!!
An investigation like that brings lots of group creativity and fun)))
(and i hate when such plotlines are eviscerated by editors, publishers, new owners that no more have the tallent to create something great but have loathing for money instead)