This was a "Champion" Capsule. Didn't people say that you get a champion of another region once you have all the champions in a region and open a Champion Capsule there? I'm
League of Legends: Level 2000, but the reward is only a champion capsule? - Not A Gamer
Opening the new CHAMPION CAPSULE from LEVELING UP at League of Legends - YouTube
Capsule (Legends of Runeterra) | League of Legends Wiki | Fandom