The Dragon's Egg is Maleficent's talisman.
The Dragon's Egg holds the powers that were stripped of Maleficent when she was brought to the Isle of the Lost. It along with the "Ring of Envy", the "Fruit of Venom" and the "Golden Cobra" were awakened when Maleficent escaped the Isle releasing large amounts of magic that had been building up underground. The actual talisman is whatever is inside the Dragon's Egg itself. The weapon inside the Dragon's Egg has to hatch, it is only able to hatch if it is sat upon by a dragon.