What are your thoughts on a thief Champion?
While some Champions have, in lore, been thieves at one time or another (Janna, Graves, Talon, etc.), no one has kept it as a lasting occupation. Filling in the thief archetype is something that, I feel, should've been done a long time ago.
How would one make a thief? I'd have it revolve around "stealing" gold, but since gold theft is a toxic mechanic, I would compromise by using the same mechanics as Spellthief's Edge. Namely, you poke someone, you get some money. And from the money you "steal", you would actually get more damage power, not just power from items.
Yes, this sounds like a hyper-carry in the works, but League doesn't have enough of those (just Veigar and Nasus). It could be a lotta fun, though.
To illustrate the case, I have a concept on Reddit that has such a mechanic:
http://www.reddit.com/r/LoLChampConcepts/comments/28r8av/ritz_the_princess_of_thieves/
Drop by if you want.