An Invader's Scourgestone is the insignia of the Scourge's elite troops. These are sometimes found on the stronger of the troops positioned in the Plaguelands. Slaying such a creature is indeed a challenge, but one that should be relished with a commission to vanquish evil. The Argent Dawn currently offers a valor token in exchange for ten of these insignia. Bring them to me here, and I will make sure you receive your just reward.