Sally A. Laughlin 
Revenge Of The Demon [EPUB ebook] 

A vengeful Master Demon has returned to Mystovia with a skull he stole from the Land Between. Magnifying his powers, the magical skull enables him to control the deadly dragons of the sea, and the war-hungry dragons of the forest.
Ordering them to wage war against the peaceful but powerful mountain dragons, the demon plans to take over Mystovia while plotting his revenge against those that killed his mate.
Kess and Mac are unwittingly pulled into a deadly plan devised by the Master Demon. Deception and danger await them, as they try to rid Mystovia of the demon’s invading forces. Their only hope to defeat the enemy may come from an unexpected and surprising source. But is it already too late?