Re:
Zone of Truth
I don't know what you mean by "enforced properly" but just off the top of my head
1) Nothing forces you to answer a question
Questioner: "Failure to answer a question will be interpreted in a manner highly unfavourable to you."
2) Giving an NPC a quirk such as referring to themselves in the 3rd person can be utilized with a false identity. "The Great Flannegan would never betray his fellow man!" Sounds like it is open and shut truth... but what Zsarl says about the Great Flannegan doesn't apply to Zsarl
3) Most people aren't trained interrogators and it is trivially easy to answer questions in a way that sounds honest, but is deceptive. Player's might not catch someone answering "What is your name" with "You may call me Timothy my lords, unless you prefer a different name?" Which doesn't actually confirm the kid's name is Timothy. Or a question of "Do you mean us harm." could be answered with "Not right now, but if you lay a hand on me I'll gut you." Which again, is a true answer, but could obfuscate the actual intent.
2 and 3 overlap with the name piece: if someone gave me the answer "You can call me Timothy (etc.)" I'd ask the question again: "What is your name?". Continued obfuscation would end the interview real fast.
4) Magic items that block it, but that's cheap
Indeed, but they do exist.
5) "Well, you never asked" type situations. You could ask "do you mean us any harm in the future" and the person can honestly answer no, but you didn't ask if the demon hiding in their shadow means you harm, so you can't uncover that with a Zone of Truth
"Well you never asked" situations are usually the fault of the questioner, who should have asked unless it's really obscure (and a demon hiding in someone's shadow would to me qualify as obscure).
Or we could not equate doing good deeds, helping people, and growing in personal power as an inevitable slide into assassins interrupting your breakfast every third sunday. Because that's kind of boring. And ridiculous.
And realistic. Not every third Sunday, though: I'm trying to defend against it happening once, because once is all it takes if the assassin is successful.
That, and the definition of "good deeds" very often depends on whose side you're on. The character of mine I'm referring to here has been in parties that have done covert ops in an enemy nation that have resulted in some serious messes being made - all "good deeds" to us and our home nations but not at all good deeds as seen by the place we were messing up.
And we-as-PCs already know that nation knows who we are (or thinks they know, their info is a bit inaccurate) - at one point we stole a copy of a supposedly top-secret intelligence brief that had half our names in it along with some half-decent sketches of some of us, though the matching of names and sketches was largely out to lunch.
And we also know this nation has the means of reaching out halfway around the world to screw with us.
So yeah, a bit of good old-fashioned paranoia ain't always a bad thing.
Exactly. You wouldn't trust. So the next NPC passes by, and then the next, and it becomes a self-reinforcing cycle where you are constantly on watch for spies and trust no one, so you never actually get the chance to encounter good people or relax. Because relaxation is a knife to the back.
Expect it when you least expect it.
