Avangion

If turning into an Athasian Dragon is the natural end point of an epic-level Defiler-Psion, then the Avangion is the opposite end of the spectrum: a powerful Preserver fully internalizing their psionic studies, and transforming into a being of energy and light.

While statted out back in 2e alongside its Defiler counterpart, it's pointed out that unlike the Dragon of Tyr, the creation of an Avangion is just a theoretical possibility; no one has actually completed the necessary steps to turn into one as, much like the phases of turning into a Dragon, each phase is fraught with the chance to outright fail.

On the bright side, at the very least none of the phases turn the Avangion into a raging ball of RAGE and MURDER.

Not for the lack of trying however. So far, there's only a single named NPC who's working towards becoming an Avangion: Oronis, the Sorcerer-King of Kurn, the only of his fellows who felt remorse at the atrocities he committed under Rajaat, and worked to truly make up for what he did. Depending on the source, he's already halfway there, or managed to completely complete his apotheosis into one.

If you're one of the ones working under the idea that Oronis actually succeeded, then his very existence becomes a veritable game-changer for Tyr, and the setting in general, as it represents the first real chance for the environment of Athas to completely recover. Not that it makes things any easier -- not only is the Dragon of Tyr still around, but Oronis would stand alone against all other Sorcerer-Kings and their forces. But in Athas, some hope is better than no hope at all.