The Undying do have the power to distract and feed off people though. That’s not false power. Soo – you think Euron’s a victim of this magic rather than a practitioner because you think he’s BR’s failed apprentice? But does that really mean he can’t use magic? Take a knight who trains his squire in both chivalry and arms. Just because the square rejects chivalry that does not mean he is incapable of becoming highly skilled in arms. There are plenty of monster knights who testify to this.