@Draco-knight-Blaze
Yes, it is a crossover with the League of Legends character Diana (also called Scorn of the Moon).
With her crescent moon blade, Diana fights as a warrior of the Lunari - a faith community that had almost disappeared in the lands around Mount Targon. She wears a shimmering armor in the color of the nocturnal winter snow and is the living embodiment of the power of the silver moon. In her pulsates the essence of an aspect from beyond Targon’s mighty summit, and Diana is no longer purely human. She struggles to understand her powers and find her destiny in this world.
The artist of this fanart seems to be a fan of this character. And the colour design goes very well with Starlight. ;-)