Xayah and Rakan skin concept
I had an idea about a Xayah and Rakan skin combination Chemtech Xayah (becouse of the darker colours she has and plague doctor theme would kinda fit here) Piltover crafted/Hextech Rakan (becouse of the yellow/golden looks piltover machines have)
There could even be story to it something like : Since beings in vastaya are being hunted becouse people are scared of them maybe someone from zaun wanted a test subject and xayah and rakan falled into a trap. And they got theyr magic taken/extracted from them and someone putted them into a hexcrystal. Xayahs crystal was taken and replaced with chemicals meanwhile someone found Rakans and used it to power Rakans rebuilded body after the experiments or something like that
Anyways i got idea from a Mr and Mrs. Smith and theyr steampunk rebuilds https://steamuserimages-a.akamaihd.net/ugc/147885780457295423/059E6773D19C23F088531F026E04C6EFB1F6C5F2/?interpolation=lanczos-none&output-format=jpeg&output-quality=95&fit=inside|1920:*