I don't have a concept art, but I would love to see a Sejuani skin with bristles being an elephant!
Both dressed up for India's Holi festival.
When she spins her flail around, the colored powder goes around or something cool like that xD 
Sejuani needs more skin, so it would be a great idea I think :)
Something kinda like this, sorry for using paint xD
The spray paint is the Holi colored powder they use, and they would throw it around and it would burst with her E. Oh and her R would shoot out colored powder. Would be so cool~
If not this theme, any elephant skin would be the KEWLEST ^_^,
There's bear bristles, so why not elephant :D
There could be a whole group of Holi champion skins.
