In this event your goal is to collect leaves from the levels. To collect a leaf you will need to break the block containing the leaf icon. In order for the leaves to be counted you will need to complete the level successfully.
During this event you will be added into a leaderboard of 20 players. The players that collect the most leaves will be rewarded at the end of the event. The event ends after the timer has run out. You can see the timer on the event icon on the left side of the main screen, as well as on top of the event leaderboard.