"If they are so dangerous, why did the wizards there not deal with them?" Graymane demanded. "Why did they not use their magic to end the threat"
"Because the orcs possess magic of their own," Antonidas countered. "Potent magic. Most of their warlocks are weaker than our own wizards, at least from what my fellows reported, yet they have far greater numbers and can work in unison, something my own brethren have never found easy." Khadgar was sure he heard some bitterness in the old archmage‘s voice, and understood it well. If there was one thing every member of the Kirin Tor valued, it was his independence. Getting even two wizards to work together was difficult enough—the thought of managing more than that was almost beyond imagining.
--Tides of Darkness