The Dead Fields

Our initial scouting reports of Silverpine show the rot hides have a base at an old farm to the north, the Dead Fields. We have sent small assaults against them, but each time they are reinforced by the banshee Nightlash, who uses her magic to rout our forces. We want Nightlash destroyed. Go to the Dead Fields and assault the rot hides. If you don't see Nightlash then kill the rot hides until she appears, then defeat her. Her essence will turn to dust. Bring me that dust as proof.