Xerath different Ascension Theories

Riot threw us a good ball with the insight about the Ascension ritual so I wanted to create this thread to be a collection of theories and speculations about it and why Xerath had such a different ending.

What we surely know is that Ascension is bound to improve your self into a powerful Avatar. and Avatars (aka the Jackal and the Crocodile) fit well their roles, they both are warriors but Nasus was also a warden of the wisdom of Shurima (unless the Lore gets more retconned). assumed the regal form of the Falcon. In his case, the armor he was wearing resembled it and we can leave a spot open on if it was a determinant factor or just another reflection of Azir's Avatar, how he was envisioned and so the meamorph into the falcon was just a known consequence.

Now, Xerath...

He was really different from all who attempted the Ascension ritual, he was probably the first and only Mage attempting it and already had great powers.

I'll add an extract of Jaredan comment about it: "He knew more about the Ascension ritual, what was needed to disrupt it and the power that resulted from it than anyone else at that time. That didn't happen overnight, and it didn't just happen through the course of revenge. Xerath's rise was self-made, not just through his involvement with Azir as a child—and how that elevated him from his low position—but also from his own aptitude and ability to gain knowledge that was lost to virtually everyone else. An understanding he sought while under the true and perceived boundaries of his station within Shurima."

We know that wanted not only to Ascend, but also to make it a demonstration of power against Shurima and all the Golden Lords. So we can assume that rather than rotting said ritual he wanted to improve it to a point where omnipotence was closer than ever, the fact that was anyway involved in the ritual and that he could ascend millenia after can be a proof in favor of how powerful the ritual was.

Not to mention that Xerath himself might have redied his being to absorb that power without perishing. And this can give double dept to his last act:

He couldn't let Azir undergo the ritual because he surelyw asn't ready to withstand it in the form Xerath had prepared both because of the plans of vengeance and for not letting it destroying completely Azir.