Star Guardian Kayn?
https://78.media.tumblr.com/f4d1a8180900acb8a4a216bc294e0217/tumblr_p3gpwublTJ1wi2gm2o1_540.jpg
It can be argued that Star Guardian Kayn wouldn't work due to his lore and how off it could be but. In a roleplay community I came up with the idea of a Star Guardian Kayn, and someone suggested I should show it to the community. I was a bit shy about it, but I thought 'to heck with it, let's see what happens!'. My art isn't 10/10 but I tried my best lol.
This link/image is basically what Kayn would look like. I'd say the transformation to red or blue could mimic the kinda transformation you see in animes. This artwork was specifically made for the blue Kayn.
Interestingly enough, I feel like Dark Star and Star Guardian share the same verse; why not make Rhaast a Dark Star-looking champion and Shadow Assassin Kayn a Star Guardian?
Yay or nay?
main since he's out, it's definitely nay.
Your artwork is great, it actually reminds me of an elf from LOTR but the fabulousnes from the star guardian category doesn't fit the champion at all, and if Riot decides to create this skin I will be so disapointed. Kayn is a corrupted human so the dark star fits rhaast very well, but the star guardian skins are bright, pure and girly. So I hope you understant I don't want it for my champ xD
So I think his next skin must be a blood moon, a headhunter, a warring kingdom or even a championship skin. The last one could be great because his master, zed 
, has already one that looks great.
That's it for my point of view. ^^'