That’s my ruling exactly.I think the "deeply into reading a book" analogy is reasonable. Anything you might miss if you were deeply inot a book, you're probably going to miss while in a trance. Disadvantage on perception seems appropriate.
I give the trancing elf disadvantage because it’s only semi-conscious, but I wouldn’t give nearby creatures advantage to sneak. I’m too much of a simulationist for that and would get hung up on why they get better at sneaking just because there’s a trancing elf around.Not really. You aren't asking about how much water is in the glass; you are asking if there is a glass of water present or not (meaning, you either have a guard or you don't). I've been semiconscious before (I bet that lots of people who've head their wisdom teeth extracted have also been) and let me tell ya, I barely even remember getting from the taxi to my apartment.
The quality of our hypothetical guard ("the amount of water in the glass") is handled by the Perception check, right? Was he alert enough to see/hear the assassins approaching? Was he looking the right direction at the right time? Did a bird call distract him? Let's find out...roll Perception.
So maybe that's the way to do it. Instead of a flat "no you can't do that," maybe I should instead rule that if a guard isn't giving their full attention, they make Perception checks at Disadvantage. Or maybe the creatures hiding in the woods get Advantage on Stealth? Maybe both?
While I agree that disadvantage on Wisdom (Perception) checks is appropriate for being in a trance, I wouldn’t be inclined to impose disadvantage on a character just because s/he is reading a book. Mapping, foraging, navigating, or tracking, however, can get you auto-surprised in my game.I think the "deeply into reading a book" analogy is reasonable. Anything you might miss if you were deeply inot a book, you're probably going to miss while in a trance. Disadvantage on perception seems appropriate.
If non-elves are neglecting their guard duties and engaging in relatons, their passives may pick up a bit of drool from the elf’s mouth.My next question would be, how do you think this could be abused by Players? Do you think it could be extrapolated to other situations?