Eclipse Aatrox
This is an idea that sort of represents my ideal skin for this, my all-time favorite champion.
I like the Eclipse line because the only skin in it is a very cool take on an old timey fantasy knight in a bleak, dark world.
I imagine a skin for Aatrox that makes him into a fallen eclipse knight - his abilities generate particles that would be really cool for this, especially with his being fit for both lunar and solar eclipse, like Leona was.
But instead of being a righteous, active knight, I imagine him more like Artorias the Abysswalker of Dark Souls game - he did his best, but all his sacrifice really did was create a monster that does more harm than good to those he meant to protect. He has a great kit for a corrupted knight - imagine huge corruption bursting out of the ground when he uses the Darkin blade, and his true fall when he uses World Ender and the corruption takes hold - which results in some of that empowered corruption staying behind after his true form relents and he gets some of himself back.
Huge potential in new animations for his abilities here since he would be more knightly - so maybe less verticality to the Qs and more of a humanity-lost stance on his ult, instead of having his sword on his shoulder and just looking generally pissed off.
I think there’s a ton of room for a purple+steel+blue color palette and more of a rounded or amorphous particle shape for a skin for him instead of everything being bright red and sharp like his base skin. Also he could use a skin with a more traditional sword that would change when he ults - I think that particular feature of a model swap on ultimate that lasts until death was one of the coolest things Leona gave us that still sticks around with High Noon Ashe.
I would also say he would make a fine “old god” for the coven line, but I think he is very knightly to begin with and frankly base Aatrox could almost be an old god for how he looks.