Quake and crystal? Well, because they are two dragons with the same two elements, it could only breed either a crystal dragon or a quake dragon. Sorry, but that's all! Or, if you get lucky, you might breed a rainbow dragon! And if you don't want a rainbow dragon, you can sell it as an egg for 2,000,000 coins! But I suggest you not do that. Because I have a sun dragon, which is almost as rare or maybe just as rare, and even though I bred it and didn't buy it, it has paid for itself many times over! (and by that I mean it has earned me over 2,000,000.) Oh, and by the way, I am starting to put these little tips on all of my answers. Search different questions to find my tips!
You breed blazing and crystal
Breed a Crystal dragon with a Cactus dragon.
There are a lot of possibilities you could be making a crystal, sonic, quake, sandstorm, or a air dragon.
it could be anything
You get a Sun Dragon
I was trying to get the emerald dragon by breeding a crystal dragon with a linge dragon. But i got a  dragon
Either buy it for 1,425 gems or breed it using the cactus dragon and the crystal dragon in the breeding cave.
You will get a Rainbow Dragon. Hurry you have limited time!
You don't breed a Kairos Dragon in DragonVale. You have to get parts to complete it.
You can't. They're not compatible
When you breed an earth and firefly dragon, you can get a crystal, scorch, sandstorm, or firefly dragon.
you breed a ice dragon with a mine dragon