Apparently, in 1st. ed. AD&D both Liches and Vampires were immune to turning.
Now I know why it doesn’t work on them when I try it with my pala.
What’s the rationale, that they’re too powerful?
Too much evilness?
I have AD&D2e revision, 3.5e and 5e rulebooks incidentally, in the attic.
It is based against their hit dice - you can only turn so much. I think in NWN it is 2d6 + Chr modifier + level (cleric or pal, whichever is higher). * For the purpose of determining the highest level (hit dice) creature that can be turned, the turner’s level is modified (from −4 to +4) by a turn check, and no creature with more hit dice than the modified level can be turned. The turn check is a die roll: d20 + charisma modifier, plus another d4 if the turner has the sun domain.