The annual holiday schedule has been released on the forums, and with it, past Holiday dragons become temporarily available!
Holiday Dragon Breeding
Past holiday dragons will be breedable for a seven day period from December 19 at 00:00 EST to December 25 at 23:59 EST. During this time, past holiday dragons will be able to produce eggs of their breed, and have the potential for breeding multiple eggs (though you will only be able to keep one per pairing). This is unchanged from previous years.
The special Holiday biome will again be available during the same time period (December 19 at 00:00 EST to December 25 at 23:59 EST). In this biome, past holiday eggs will be available (just like Halloween, and last year). Past limits on cave-based Holiday eggs still apply (the breed limits help page will update with Holiday dragons during this time to help clarify).
New Holiday Dragon
A new holiday dragon will be available starting at 00:00 EST on December 25. It will drop for exactly three days (ending on December 27 at 23:59 EST); after this time it will no longer be available from the cave. There will be a limit of two of these eggs from the cave.
This year's holiday event will begin at the same time as in past years: 12/25 at 00:00 EST (the same time as the new dragon), and will run for seven days. This year's event will not require daily participation (but hopefully it's so fun you want to anyways).