Strings of the Puppet Masters

I understand you were just here to deliver the vellums, but we could use your skills as a ‹class›. Our forces can only hold back the demon invasion, disallowing us to send anyone further into the enemy's camp. The stronger of their forces stay in the back, commanding from a distance. They carry enchanted runes to keep control over the frontline demons. I would very much like to study one of these runes. Please retrieve one for me, so we may learn from it and use it against the Legion.