Q: Dear Sage
Are thinking undead such as vampires and liches immune to mind-affecting spells? If so, what is it about becoming undead that changes the way the mind reacts to spells like charm monster?
A: Yes, all undead are immune to mind-affecting spells. As to why that’s the cause, many sages have theories but no one knows the real answer. Some suggest it is a boon granted by Vecna or Orcus, while others believe it is a side effect of the creature’s defiance of life.