This quest grants access to Bloodskull Valley: The Excavation Site, a special instance of Bloodskull Valley. It is given by speaking to a Fallen Blackguard at -12, -44, 247 in the Commonlands.
The first thing you need to do is kill the Bloodskull Messenger in the Commonlands. He is located across the river across from the Ruins of Val'Marr.
After this you must gather four mineral deposits. These are ground spawn not too far from the entrance of Bloodskull Valley in the Commonlands:
Bring these to the Fallen Blackguard to be granted access to the zone. It is entered from the same location as the other Bloodskull Valley entrances.