Runestone

From WoW: IncGamers World of Warcraft Wiki

Monolith constructed on Caer Darrow in Darrowmere Lake near Quel'thalas by the ancient High Elven druids, inscribed with magical runes of protection. Gul'dan seized it and ordered that it be cut into slabs and used to construct unholy altars. These altars gave life to the Ogre Magi. There was 7 runestones in total protecting the borders of Quel'thalas from any outside threats.