Ice Breath of the Earth — Elizabeth Klein

Everything hinges on the success of Dougray and Robbie, orphaned brothers and fugitives, to lead King Morgran's soldiers on a wild goose chase to the Groaning Rocks, a place of demented souls. Attacked by a black dragon, they are rescued and given shelter by Alysam, an exile from Alpinia. But all is not well. Dougray is infected with dragon venom and begins to turn to stone. A desperate race for survival begins as the dragon pursues them through the underground passageways. Found by Navarre, last of the Healers, Dougray is restored to health and the brothers are then offered a place of safety in the treetops with the Elves. But an unexpected attack by the dragon forces Robbie to track it to its lair, where the ultimate purpose of their quest lies: the retrieval of the third crystal.