Merlin's Dragon trilogy

The dragon Basil, now mighty in strength, size, and courage, seeks the cause of a new series of crises that threaten the stability of Avalon, while his friend Merlin is distracted by problems with his son, Krystallus.

The dragon Basil leads the ultimate battle to save the land of Avalon, and finally must decide whether to obey his dear friend Merlin's request, even though it means giving up his powers as a warrior.