What’s a Super reward, and how do I get it?

If you complete all the season’s levels, you’ll unlock a Super reward. The Super reward is a key that will bring you closer to obtaining a bonus reward: a mythical chest. To unlock the chest, you will require several of these keys.
Players must claim their key before a season ends, but only once they have collected all the available seasonal rewards. Please note that, to claim a key, you will require a certain number of tokens.