While you were down there I happened to notice that one of those beasts stood out from the rest. He was bigger and more menacing. I bet he's the one who led the others here to cause the disruption to the dig site.
I ask of you now one final task, <name>. See to it that Sarltooth is brought to justice. And considering the gravity of his crimes, justice in this case means death! Bring me one of his talons as proof of his death.
Thank you, <name>. Your efforts here will not be forgotten. Many innocent Dwarves died at this site, simply doing their jobs. The vengeance you delivered to those evil creatures should make them think twice before attacking King Magni's subjects ever again.