The Nullifier is a human Master Psionic or Psi-Stalker whose mental "reactive" powers have developed to provide a remarkable defense against psionics and magic. From an early age, the Nullifier has the ability to erect a barrier of mental energy that renders the character virtually immune to mind-altering psionic powers, along with the ability to interfere with and negate them. Furthermore, this defense mechanism can interfere with the mental powers of other psychics and, to a lesser degree, the powers of magic practitioners.