Long story short; for around 2 months now, probably more, the glowing/ethereal effect of the horns on Rhaast have been present in all forms of the Soulhunter Kayn skin. That means you can see the horns at the start of the game, and all the way through regardless of the form you choose. We can see it wasn't meant to be that way from the original videos Skinspotlights did on this skin, as well you can see it should not be present by looking at the Riot official art for the skin. Am I the only one that's noticed this? It's pretty annoying, having that hang around even when you use his shadow assassin form..
Better question is, since I'm well aware this has been posted before, how has it gone for what looks (upon further investigating) to be nearly half a year without being addressed? It's disappointing to purchase a skin and have it be broken visually for so long, without even a hint of reasoning.. :/
Edit: Taken from another post (https://boards.na.leagueoflegends.com/en/c/bug-report/Ax0lMaWW-soulhunter-kayn-horns-visual-bug-gameplay), here's what we're seeing =-=