Chromie said the relics you gathered are reagents to a powerful spell, and one more is required: skulls from the scourge who took part in the battle of Darrowshire.$B$BTake this crystal and hunt scourge champions for their skulls.  The crystal is enchanted; if a champion took part in the battle, then when you pass the crystal over its skull it will resonate.  Bring me those resonating skulls.$B$BGo, $N.  You'll find scourge champions in the Noxious Glade to the north and the Fungal Vale to the west.