As another suggestion to go with the LE dragon theme: "SETS!!!!!"
So basically whenever there is a release of LE dragons, there would be an additional bonus or 'gift' dragon for completing a 'SET'. For example, getting a "BOO" + "Pumpkin" dragon = 1 Halloween set. "Snowman" + "Elf" dragon = 1 Christmas set. This'll drive us more nuts and have some laughs