User blog comment:Reilock/Riots new Lore Direction: Rant/@comment-3286233-20140924001503

For Xerath case, he wanted to ascend, but since Shurima didn't (or wouldn't) face any dire threat during his lifetime, he might fear that he would die of okd age and be forgotten. His thought were probably:

"What if the Ascension process could be done without facing the dire threat?"

As he Ascended with wrong ritual performance, the Sun Disc probably corrupted Xerath's Mind (in similar Brand did to Kegan Rhode) and cause the Shurima fall in ruin. Azir would have faced the same thing as Xerath if Azir too did the wrong ritual.

How Renekton got insane is probably Ascended effect caused by Xerath. It's like giving them red kryptonite.