Orthog has realized that he is under attack and will seek Talion out. He remembers your previous encounter that resulted in his scarred face, and he takes this quite personally. The premise and flow of the battle is defined by your earlier actions and how you handled his henchmen. Depending on whether you chose to kill Ratbag or allowed him to escape, the encounter will play out differently.
Surviving a battle like this with such a large crowd can be very difficult. The key to insuring success is make sure that enough of the army is under your power, as well as blocking incoming attacks at key times and using area-of-effect attacks.
Trivia
- Orthog Troll Slayer had a previous encounter with Talion. During this encounter, Talion burned his face. Orthog is now burning for vengeance against Talion.