Horn of Dagoth
The Horn of Dagoth was the horn belonging to the god of the same name. When Dagoth was defeated in a battle with other gods his horn was torn off and fell to Earth, where it was found by humans who worshiped Dagoth. These humans subsequently founded the order named the Keepers of the Horn. The horn was inlaid with gold and decorated with jewels by the Keepers, and kept inside of a stone dragon's mouth in their temple.
At the behest of Queen Taramis, Conan, not knowing what the Horn was to be used for, stole it from the Keepers. The Horn was taken back to Shadizar by Bombaata and Jehnna. There, Jehnna placed the Horn into the forehead of Dagoth's statue, resurrecting the evil god. As the Horn was the source of Dagoth's power, Conan had to rip it off again in order to defeat him.