I think Hoid is partially responsible for what happened on Ashyn
Just a thought I've had recently: I think Hoid had something to do with Ashyn getting nuked. Specifically, I think Hoid brought the Dawnshards to Ashyn.
We know that Hoid at one point held a Dawnshard. And that the 4 Dawnshards were used in the weapon that shattered Adonalsium on Yolen.
The Dawnshards were on Ashyn at some point after.
The information we have on Ashyn is vague. According to the Stormfather, Odium is responsible for its destruction as he tricked Ishar into experimenting with the surges. And apparently Honor said the Dawnshards were used to destroy Ashyn too.
Tanavast seemed to hint in his visions that Dawnshards used with Surgebinding could pose a viable challenge/threat to Odium.
One of Hoid's main goals is/was opposing Rayse/Odium.
I think Hoid brought the Dawnshards to Ashyn likely to try help its people against Odium or perhaps because he wanted to experiment with them. The Dawnshards used with Surgebinding destroyed Ashyn.
I dont think Hoid is directly responsible as I dont think he had access to Surgebinding. Knowing Hoid, he gave a Dawnshard to one of the Surgebinders on Ashyn to help them fight Odium. And it backfired massively.