Rat is one of the three skins released in the Season 3 (Chinese New Year) event. It could be acquired for a limited time as part of the main event from mid January to early February 2020.
Rat could be acquired by collecting 40 tokens and by purchasing a Golden Pass for $4.99 during the event period. There may be few opportunities to acquire this skin in the future.
Details of this skin may vary depending on location, platform or time.