This event is available for all players that have completed Alfred's house (the first chapter of the main story). "Ancient Scroll" event starts on Monday every week and lasts 48 hours from the moment you have started it.
During this event you can receive various boosters and additional moves. To do so you need to win match-3 levels. Each time you win a level, the next scroll opens up.
Please note that to reach the second and third scrolls you need to win levels in a row! Each failed level sets the "Ancient Scroll" back to zero.