Joker Dragons are special Dragons that are used for certain Breeding Events. They are unique Dragons that are experts in the breeding the Dragons you want in these types of events. In future special breeding events (NOT in all of them!), you will be able to use it as your ‘Joker’.
For example, imagine that in a future special breeding event you are missing one of the needed dragons for a special breeding combination. If you own one of these unique Dragons, you may be able to use your breeder specialist instead! Not bad at all, right? :)
You can always find out if this event allows you to use one of these Dragons by checking out our Facebook fan page at the time of the event by clicking the link below: https://www.facebook.com/DragonCity/