Kill a Horde Hero.
Look, you're tough. Tougher than the rest of the men and women I've got here. Which means I need you for a special mission. The Horde is throwing their best against us. Heroes of their armies - Blademasters, Tauren Chieftans, you name it. I need you to go take one out. It'll be a huge blow, not just to their offensive but also to morale.