There are many combinations that will work, but my five favorites are cold and hail, cold and storm, hail and lightning, hail and storm, and lightning and storm. You have to start breeding the dragons between 7:00 p.m. and 7:00 a.m.
You have to breed a sun and moon dragon together
You don't breed a Kairos Dragon in DragonVale. You have to get parts to complete it.
you breed a ice dragon with a mine dragon
You have to breed a plant and a fire dragon.
As of July 2012, there has not been a star dragon in DragonVale.
I got mine with a magnetic dragon and a lichen dragon and got it while trying to get another apocalypse dragon.
You have to breed a metal and a water dragon together.
You have to breed a plasma dragon with a salamander dragon.
Breed the earth dragon with the fire dragon.
To get a Smoke Dragon, breed a fire and air dragon together.
There is no "marsh" dragon in dragonvale but if you are referring to the moss dragon the best way to get it is earth and plant, although you also have a chance to breed the tree dragon.
Breed a Crystal dragon with a Cactus dragon.