How do you breed a rarest dragon in DragonVale?

the rarest dragon on dragon vale would have to be the fire dragon because all the other dragons you have to hack for. NO. You don't have to hack for it, you can BREED it, the rarest is leap year or rainbow dragon because leap year comes after 4 years or so, then rainbow is rarest of ALL. Breed Mud And Blazing AFTER few tries and it WILL work, only for rainbow dragon. DONT LISTEN TO HACKERS, THEY BREAK YOUR GAME YOU MIGHT RESTART YOUR GAME ALL OVER! Try looking at google because it's true nearly ALL the time.sometimes panlong dragon for mud blazing...