The Dragon's Touchstone by Irene Radford

THE MAGIC WARS--
Three hundred years before the time of The Glass Dragon, Coronnan is a kingdom at war with itself. Magic is wild and magicians uncontrolled, each working separately for his own goal. At the height of this age of chaos, the dragons know they must intervene. Their chosen humans are:

Nimbulan, a soul-weary Battlemage who has nearly exhausted his own great abilities in the endless battles of succession between rival lords. Determined to find a better way, he founds the University of Magicians to train and unite the next generation to stand against the rogue spellworkers who prefer endless war and the wealth and power it brings.

And Myrilandel, a witchwoman and healer who will become the liaison between humans and dragonkind, offering the gift of dragon magic to Nimbulan and his fellow spellcasters.

But even dragon magic may not be enough to defeat the greed of Nimbulan's most trusted assistant, the fanaticism of a priest who thrives on blood magic, and the ambitions of the lord to whom Nimbulan had once given his allegiance...

This book is part of the "The Dragon Nimbus Histories" series.
Here are some other books from this series: