Amulet of Vathelos

The Amulet of Vathelos is a mystical relic created by a warrior-wizard named Vathelos. It can absorb certain kinds of magic, like Set’s power as well as undo spells casted by Set or his servants. The Amulet also protects its wearer from certain malevolent magic.

It was stolen by Con, Conan's grandfather, from a Stygian cult who worshipped a demonic entity known as Azaroth, and was in service to Wrath-Amon.