I wanted Saphira to be not only so I designed this guy. He is a half goblin named Marlin who was shun from the society of goblins because of his "humanly looks and behavior".

He'll come across a few troll witch doctors, who will teach him the art of magic and brewing, before Saphira would let him accompany her while he was selling potions on a sudden fateful day.
Marlin is only an adept to troll magic and he has further more to study on magic from a reliable source: The mentor of Saphira and Guardian, Medivh.