Heh. It would be fair to say that at its heart it *was* a banal goblin encounter; I saw it as part of my job to try to keep the players from noticing. My primary weapon-of-choice was window dressing.Physics Guy wrote: ↑Mon Feb 20, 2023 10:28 am... what could have been a banal encounter with a handful of goblins ...

(I'm only quoting this out of admiration for the sentence -- you got your money's worth out of that one.)The platform was a feature in one of those "obstacle course under the Thieves' Guild" deals full of improbable traps and don't-think-too-much-a-wizard-did-it civil engineering.
Ha! I've never heard anything like that before, and I'm sure it would have made me suspicious. There are tons of 'sleight-of-hand' tutorials on YouTube and other places, and it is remarkable what folks can get away with after a very little practice. Some of the moves are so simple that once you are aware of them it's hard to believe that we fall for them ... but we do. (for what it's worth -- after thinking about it a bit more I think it is improbable that *if* your player cheated it was through some sleight-of-hand trick -- why raise suspicion by asking to roll a 17 rather than simply producing a 20? Your suggestion of a slightly loaded die seems much more likely.)The player asked if he could instead simply call his roll in advance, to be some number other than 20. He wanted to pick his lucky number 17. I said OK, he'd survive if he rolled 17 instead of 20. And he rolled 17.
Your story also reminded me of this: 17 Is The Most Random Number. (17 is also the most frequently chosen number when folks are asked to pick a number between 1 and 20, which probably reflects an interesting bit of psychology. Maybe.)