I haven't seen the map, but one idea is that you could age the Azure Dragons with a spectral dragon. Also, during battle, you can use a destructive beam to reduce the defense of the Azure Dragons, so they can be killed faster. Another simple way is to control their numbers with expert blinding; in this case, the Azure Dragon won't respond to attacks from other dragons, and the remaining stacks will reduce the number of Azure Dragons to the desired level or eliminate them altogether.