You share an especially strong bond with your phylactery and gain benefits from keeping it on your person. You may choose to craft your phylactery into an amulet, a ring, a brooch, or some other form of jewelry. When you finish a short or long rest and you are wearing your phylactery, you may choose a damage type other than radiant damage. As long as you wear your phylactery, you have immunity to that damage type. In addition, your phylactery is more resilient than normal. Your phylactery’s AC becomes 20 and its hit points increase to 120.
Your phylactery’s nature is hidden from casual observation, and an observer must make an Intelligence (Arcana) check against your Transformation Save DC in order to identify your phylactery.