Ao Shin
Until recently, I had never heard anything about Ao Shin but after doing some research, he feels like such a missed opportunity as far as interesting champions go. I understand there were alot of problems surrounding how he fit into LoL both from a gameplay and a lore perspective but maybe if we put a fresh perspective on Ao Shin, Riot would reconsider working on him!
In terms of his lore, I feel like it would be interesting to have ties connecting both himself and Aurelion Sol. This could answer many problems, namely why Aurelion Sol feels so lacklustre in the game for the divine being that he is in his lore. Obviously we would have to retcon his lore a little bit, but here are some ideas;
I think it would be pretty cool if we explored the idea that Targon was scared of Asol, particularly when he tested the limits of their hold on him and displayed his almighty power in the lore. Maybe the idea that Targon devised a way to syphon Asol's power into a conduit dragon in order to make him more managable would be a convincing back story for the birth of a new powerful dragon called Ao Shin. I feel that this kind of story would help explain why Asol feels nowhere near as powerful on the rift.
As for abilities, I have a few ideas on new abilities, as well as how to get around abilities that were previously talked about.
The idea of toggled/permanent flight did sound cool but it also sounded very overpowered. However, i feel that a good way around this would be in the form of a passive I like to call 'clipped wings'. This passive would allow Ao Shin to go over walls, and would also toggle a flying animation. However this is strictly an out of combat mechanic only; any damage from champions that Ao Shin takes would clip his wings and force him to land. His wings would then begin to heal again when he is out of combat and after an appropriate amount of time his passive returns.
As for his thunderous origins, a cool idea for his ult / abilities would be the power to create storm clouds with one ability that does DoT when champions stand in it, another ability to move these clouds around (maybe like syndra picking up her orbs, or Viktor moving his passive), and an ultimate which causes an almighty bolt to come crashing down from each cloud present on the map.
Another idea for his kit would stray from the storm cloud idea and revolve more around the lighting emnating from Ao Shin himself. For example one of his abilities could be similar to Vlad E, where he charges up lightning over time and can release it in a shockwave to either CC or just straight damage his opponent. This could be done over a similar time frame to Vlad E, or it could start to mirror Kassadin E, where he stores charges over time ready to unleash a shockwave when its fully charged. It could even reflect Bard passive where his presence on the map causes lightning clouds to spawn around him, and collecting these fuels his spell.
I could go on more about my ideas for his kit if anybody shows interest in it, but i really think that Ao Shin has a place on the rift and I would love to play him, he has so much potential!