Riot has recently updated Swain, The Noxian General. Here’s a look at that process.
When Riot updates their champions a lot goes into it. There are pieces they may want to preserve and overall a new feel they want to bring into the champ. It’s a long process that they’ve been doing well with so far.
In this post, they answer a lot of questions you may be wondering about the process in general and for the champion specific. You can take a look here and see how they go about creating these concepts and bringing them to life on the Rift.