Ok here's my entry, I'll try to explain it but I can't assure nothing since my main language is not english.
Name: Chamaleon Cultist Clothes
Tooltip: "I swear I've seen you before"
It consists in a Mask and a Robe, they are very similar to the Cultist Clothes, but they have a more chameleon-friendly look
So what's special about this vanity? First of all to craft it you must prove that you visited every single biome in hardmode, so you will need ichor, beetle scale, frozen, pixie dust, ecc. ecc.
and of course have the cultist robe to combine them all in a loom.
I only created sprite for the main surface biomes and for mushroom because I looooove mushroom, but the concept can be extended to every single biome in the game, so basically every time you enter a different biome a smoke like effect will appear around yourself and the vanity will change accordingly to the biome you are in.
I'll try to explain them quickly because even if I tried my best my sprites are not the cleanest
Forest: A flower will grow on the mask, when robe's equiped small fake pumpkings will grow around you when you walk
Desert: Sun will follow you and you have cool glasses, fake cactus will grow
Snow: Snow will accumulate and ice will form on the mask, robe will produce snowy particles around you
Jungle: Nature's gift or a rose will grow on the mask, stinger will pop out of the ground (they will not hurt they are just aestethic) and spore particles around you
Hallow: Unicorn mask and particle effect just so you can blend in with them unicorns
Crimson: You now have horns and an evil face, robe will emit ichor particles and ichor will come out of the ground
Corruption: You have eater's mandibles and one eye, robe will emit purple particles and cursed flame from the ground
Mushroom: Mushroom on the head, spores and mushrooms from the ground, perfection itself
And that's it for now, space could have little ufo on top, underground a light helmet, hell can have smaller horns and maybe emit smoke, marble and basalt can pick up inspiration from the respective enemies (a gladiator helm and a very cool eye from the marble dude); blend biomes like snow hallow can mix up the alredy existing skin i will attach here.
I though about this skin just because i like changing my look A LOT, so having a vanity that can change it instantly will be amazing.
Only problem will be with dyes that will ruin the color change part, but maybe having them change only the emitters will be a good compromise.
Anyway, winning or not, i had fun creating them, keep the work up everyone not much time left!