Those Art Spotlights became a bit of a burden: Artists had to remember to record, the need for editing and the fact that more than one artist may work on some splashes.
Anyways, Riot artist Keinan Lafferty (Who goes by the name Riot Knockmaw) has a YouTube channel with wonderful and very insightful tutorials and vlogs.
Here are a few videos of him painting an unofficial/'fanart' Ahri splash and explaining the process that went into it:
https://www.youtube.com/watch?v=lrVqNXdRysg&list=PLb0T1WxEbeAIX__krnmGiqEY7WJAYsvEX
He was previously a Splash Artist at Riot but moved to a Concept Artist position- He's known for things like the first Ahri and Talon classic skin splashes, Fizz's splash, Diana's splash, Battle Bunny's Riven concept and splash, Maokai's VU concept, Miss Fortune's updated Waterloo and Cowgirl skin designs and many, many more. :)