This is an Ancient Tablet forged into the rocks of the Golden Gars King.
Kill 15 Gars with the Gars Slayer and use the item to open the door to the Banshee Queen's Lair. Located just east of the Gars location.
How to Obtain
Drops from Golden Gars King
Kill 15 gars while equipped to enter the Black Citadel - Banshee Queen's Lair