Black Orcs will only follow the biggest and strongest leaders, which in their opinion means another Black Orc. Black Orc Bosses think the same, and will surround themselves with their own elite mob of hand-picked Black Orc boyz.
Your army must include one Black Orc Boss for every Black Orc Mob it includes, and vice versa. In other words:
• For each Black Orc Mob your army includes, it must also include one Black Orc War Boss or Big Boss.
• For each Black Orc War Boss or Big Boss your army includes, it must also include one Black Orc Mob.