Nezumy, the Clever Mouse is a fan-made champion concept for League of Legends
Nezumy is Nazrinfrom Gensokyo. She somehow found her way onto Valoran through the Void, and lost much of her memory along the way. She fights with the League of Legends in hopes of restoring her lost memory and returning to the place she once called home. Remembering only her adept treasure hunting skills and diligent engineering abilities, she brings a large amount of utility and strength into the Fields of Justice as both a solo laner and support.
While the backstory is somewhat cliché, I tried to use logic that would explain why Youmu's Ghostblade and Wriggle's Lantern are both available on Valoran; I figured the worlds must be connected somehow. This lead me to the Void, the space between dimensions where time is nothing and space is endless. Due to the lack of temporal existence, it would make sense for a non-voidling entering the void to remember little of their previous reality.
While most of Nezumy's abilities are straightforward, Geomagnetic Lift [R] might appear strange. While the ability snares all those within the target area, the snare also acts as a knockup and triggers airborne-based spells such as Yasuo's Last Breath.