In other say, combine an existing theme with an champion. Examples:
Wildfire Syndra
Blood Moon Syndra
Cosmic Reaver Xerath
Void Xerath
Infernal Azir
Nutcrackzir
etc...
Let's see the ideas, may be we can guess right a skin!
Hand of Noxus 
and Snow Day , where we see a living Sion and a metaphorical/literal snow plow Sion.
Infernal 
where she takes on the form of a demon of vengeance or something.
Chosen of the Spoon 
where she has a huge spoon and is a cook in training.
Haunted 
where he's a stone statue tomb angel kinda thing that's been taken over by plants and now walks among the living.
Oktoberfest 
because I wanna see how they do Sona with an Accordion.
Winterborn 
which I picture as a sort of Freljordian interpretation of Bard, where he's like an iceborn, wields a traditional Freljordian horn and has little ice meeps. Also Mr. Saxo, because that song made me think Bard's look awesome in a tux, with a sax.
Geomancer, Fire keeper, (insert sport here) master, Storm Crafter, Cosmic , I could go on. Just replace what her orbs are made of and you're good for a Syndra skin.
Dragonslayer 
and 
, where Kha'Zix evolved to be a super dragon bug thing, and Rengar had dragon armour. I recon he'd definetly be kicking in that AU, I mean come on, is Rengar gonna miss a chance to hunt dragons?
Some skins for when 
were still alive would be nice too, even though some might be a tad more difficult than others.
I could go on but I feel like you get the jist!
Running back
Brad (Bro )
and 
, but with their outfits swapped
Gauntlet of the 5th age 
Nagakeborous 
warring kingdoms &
Azir summoning terracotta soldiers and hecarim being an animated samurai armor/centaur with a naginata.
Star Guardian Kog'Maw skin that vomits rainbows.
Trained Dragon Kog'Maw.
I'd like a Vandal Jax skin that looks more like this:
http://pre05.deviantart.net/f0a5/th/pre/f/2015/157/4/5/the_vandals_by_vegacolors-d8wb2nz.jpg
Credit to artist: Vegacolors.
star guardian urgot
Seeing for the first time flailing at all the everything all around.
Definitely not Jinx. As in, in a police outfit.
Definitely not Vi. As in, as Jinx is by default.
Young Mind Akin to a school uniform, with a singular lensed eyewear. Do have some curious ideas as to what his abilities could look like too.
And the definitely not series: Wjere Demacians would be Noxian and vice versa. Maybe even for other opposing lands. I like what I did there mhm mhm mhm
Arcade 
Frost Thorn 
Wildfire 
Snow Assassin 
A malzhar skin with particles ( bright one red/ yellow/ orange) so blood moon, forsaken, dragon tamer
Blood Moon 
and 
More Star Guardians(They did it with Project so why not?)
Jekyll and Hyde 
Reverse and 
Mongolian Deathworm
(This was real one of my dreams)
Battlecast._ Think about it..._
Empress / Hextech / Celestial / Secret Boss Syndra
Order of the Eggplant 
Reaper Zed
Sandstorm Zed
Unmasked Zed (you can't not want this to happen lol)
Void Elise
Cyber Elise
Forsaken Kassadin
Overlord Kassadin
Demonblade Yasuo
Blood Moon Yasuo
Fisherman Yasuo
Hitman Talon
Full Metal Talon
Thousand Blades Talon (Ultimate Skin)
Blackheart Ryze
Chaosborn Ryze
Nude Beach
Blood moon; Some crimson, white hues would suit him and the Oni mask circling above a champ during his let would be awesome
Dia de los Muertekaiser; I'd be a cool way to embrace the whole Brazilian Meme and Morde lacks "fun" skins
Superb Villain Mordekaiser; Who wouldn't love him twirling his mustache and wearing a top hat?
Justicar Mordekaiser; A "good guy" Morde skin could be fun^^
Lunar Revel 
Deep Terror 
Arcade 
Championship 
A more colorful skin really. I know she is a demented, evil kind of champion, but she has so many amazing opportunities and concepts that could really look awesome.
Anything 
Okay not not being a Salty Asshole, how about 
or Boss skins? Arcade 
? Maybe give a Blood Moon skin?
Order of the banana Diana.
Hextech Poppy, but she's being replaced next patch...
Cottontail
K-9 
Superhero 
Project
Pool Party 
(pool noodle OP)
Blight Crystal Sion
Bioforge Sion
Glacial Sion
Forsaken Sion
Oni Trundle
Underworld Trundle
Hip Hop Mordekaiser, his mace looks like a giant spiky microphone and he says something like "I like my weapons how i like my music, Hip and HOP" (ok that sounds kinda weird, im not good at this)
You can see what i mean when you look up: Urban Rivals LAETITIA
Succubus Morgana
Demon Morgana
Fairy Morgana
Knight Hecarim (like the chess piece)
Star Guardian Soraka, I need it.
