User blog comment:LEGENDARY PLAYER10/How to Breed Crystal Dragon ??/@comment-24231502-20131130144850

It's a Legendary, so you have to breed two Pure types for it. Sadly, using Pure Hybrids doesn't seem to skew the results toward one specific Legend or another, so it'll probably take a lot of patience. That is, unless you're feeling lucky...

Best of RNG to you!