I work on Riot's Creative Design team! We work very heavily on champion production. Many of us spend our time creating and refining champion concepts, defining a champion's personality and theme (these elements often largely inform champion art and design direction), and maintaining/developing the League of Legends intellectual property. My specific responsibilities often include writing champion biographies as well as defining, writing and directing a champion's voice direction and script.
I also get trolled by Skribbles and Harrow regularly. : ( It's probably in my contract at this point...