Why can't they be warlocks? It only makes perfect sense that other than spiritual "magic", the only other kind of magic warlocks should be capable of is ELEMENTAL magic. Not only does it innately makes sense when you picture one, but it's also logical as most of their tribes are raised through hardships up north, they are bulk and strong enough to understand the powers of earth, and so on. I mean, come on! there can be GIANT warlocks, the less intelligent race of all the game, there can be griffon warlocks, the most naive race of the game, and there can't be minotaurs? If nothing else, their raging nature would guide them to this kind of violent magic.
My two cents.
