From Elminster's Ecologies: Appendix IIIa
"Marileths - while this is apparently a legitimate form of demon, it is one that only an exceptional few have encountered and survived. The Marileth is a six-armed demon with a human female front half and the back half of a snake. She is incredibly quick and deadly, and on top of her martial prowess with six swords, she casts spells as well. Fighters should beware: in addition to being immune to normal weapons and minor enchantments, this demon also likes to cast Immunity to Magic Weapons...which must be dispelled if a fighter is to have any chance with his armaments.
Is the Marilith's behavior from atweaks' PnP Fiends component consistent with this description? Protection from Magical Weapons isn't listed as an "at-will" or "limited-use" spell-like ability for Mariliths on this page. Obviously, the PnP components strive to bring Baldur's Gate elements into alignment with their PnP counterparts insofar as that's possible (and I applaud your diligence); I don't think 2nd Ed. mentions Mariliths casting "Immunity to Magic Weapons," but it isn't as though it precludes them from doing so, and after coming across this book in game and not seeing the Marilith cast it, well that would be a little immersion breaking. If your PnP Mariliths do cast Protection from Magical Weapons, then I apologize for wasting time.
