How to get redeemed star guardian xayah?

I'm curious about how one can acquire the redeemed Star Guardian Xayah skin in League of Legends. Could you elaborate on the steps or requirements needed to unlock this coveted item? I've heard it's quite rare and unique, so I'm eager to know the specifics. Is it available through a specific event, or do players need to complete certain challenges or missions? Additionally, is there a limited time frame within which to obtain it, or is it a permanent addition to the game's offerings?