Crystal Dragon

Breeding
You can get a Crystal Dragon by breeding two Rare Hybrid dragons with each other at the Breeding Mountain or Ultra Breeding Tree. These are:
 * Earth Dragn
 * Fire Dragon
 * Electric Dragon
 * Ice Dragon
 * Dark Dragon
 * Metal Dragon
 * Plant Dragon
 * Water Dragon

Note that no combination is 100% sure when it comes to getting a Crystal Dragon. It could just as easily result in a Legendary Dragon, a Mirror Dragon or a Wind Dragon, in addition to every whatever could be made from the elements used. Legendary dragons are hard to obtain and you need a lot of luck to get one. For more information on the Rare Hybrids, see Breeding Rare Hybrids.

A popular combination that seems to work well for many are: Gummy Dragon + Cool Fire Dragon and Soccer Dragon + Gummy Dragon. The best way is to mate two Cool Fire Dragon's, which only take 4 hours to breed them together and the chances of getting a legendary is much higher.
 * Speculation only:


 * Please note that no combination gives a 100% chance of getting a Crystal Dragon or any of the Legendary Dragons.

Damage Calculator
Legendary type attacks do elite damage to all Elements and double damage to other Legendary. Legendary takes normal damage from all Elements, double damage from other Legendary and none from Fighting.

Counter Dragons
If the Crystal Dragon went first, then you've lost(unless you have two other legendaries). Only a Legendary can stop it effectively, and even they will be destroyed by 1 Legend Spell if the Crystal Dragon is equally leveled.

Trivia

 * This Dragon Produces Ice and Crystals like Ice Dragon