Black dragons are warriors. They are strong and capable in battles of force, but also ample magic users, capable of devastating opponents with their spells. Their bright eyes give them excellent night vision, which is why they generally hunt during the night.
PhD is a scientist who studies magics. He earned the name PhD from fellow dragons during the wars; Battle Scarred and Master Sargeant proclaimed him a philosophical daydreamer when resting between engagements, and the initials stuck. Since then, he fiddles about researching such spells as will make an old battle dragon's life easier - with mixed success.
PhD came up with a spell to summon beasts over to him for easy hunting. He cast it while on a mountaintop to see what creatures might come. He wound up getting mountain goats bleating all around him, some of them even jumping up onto him and butting him. They made for a nice feast with his old war buddies.
Another time he tested a spell of speed on some birds; apparently it sped up their digestive systems as well as their flight, for they flew overhead pelting him with their droppings and then zipped away - until the spell wore off. Now he enjoys plucking those birds out of the air for a snack whenever he sees them.