The Necklace of Tutankhumun is a magical artifact that could supposedly control the Nullifiers. The necklace was made from a special green glass that came to Earth in a comet. The Betrayer used this glass to make the necklace, which eventually came into the hands of Tutankhamun. Rassimov attempted to use the necklace to control the red comet, but failed and consequently died. S2E50