"We wish we were big". And thus, the Wish-Granting Flower grants the Crusaders their wish, and their bodies grow into adult bodies. As the Crusaders enjoy being adults, soon they learn that growing up is hard to do...
This was a really good episode! It was great seeing adult versions of the Crusaders, and the creature that ran amock was both adorable and highly destructive (sort of like an Equestrian version of Stitch).