Zombie Princess Di(ana), roit pls.
Anyway, 116 champs (not gonna rule out Jinx yet). Find the most likely candidates by cutting out the ones who already have a Snowdown Showdown or Harrowing skin. Then everyone who has had a skin come out in the past year, except for new release champs. Then also remove Thresh and Diana because they have a skin about to come out. Remove all champs with a known visual update in progress or just wont get a skin before that VU (Except Sivir) (so like Taric, Evelynn, Sion, Rammus has texture updates in the works). Yorick is getting a kit rework, so no to him. Scratch off Skarner for Battlecast and Swain for Dragon Master. Brings us to about 39 possible champs for likely picks. (http://puu.sh/4FhrF.png)
My personal picks from this list? Diana, either Sivir or Yi, Kassadin, and either Zyra or Syndra.
Riot seems to try to get an additional skin out for every champion that gets a VU soonish. Examples of this include Annie, Soraka, Trundle, Sejuani, Karma, Kayle, TF, and Nidalee. Logic says Yi or Sivir will be getting one soon, and Sivir VU could make it out for Harrowing to get a skin like TF did. Diana has a confirmed event skin in the works. If its not harrowing, its probably lunar revel, as they converted it to an event skin during production and pushed it back. These are the two most likely events you can haphazardly do that for her. Kassadin fits thematically very well and hasn't had a skin for a bit. Zyra and Syndra both have strong potential and only one skin (Zed might be a better pick, but I would rather see Zyra get one).
Of these, any kind of demonic/hellish/nightmare kass skin, pumpkin patch zyra has been mentioned already, Pumpkin chunkin' syndra, Underworld Yi, Something like Sivir in a costume akin to Headmistress Fiora, and Zombie or Werewolf Diana.
