Holy thread necromancy, Batman! Though I'm glad in a way, because this gives me an excuse to talk about a hit point tweak that I find effective, but that everyone I've told about seems leery that it's unfair and potentially abusive.
It started by playing in the G-series, in a party where a few of the guys were egregious min-maxers. After a couple of fights, the DM made some adjustments so that we wouldn't just walk over everything, and it seemed to work. After one session, I asked him about it, and he said he was basically just doubling the monsters' hit points.
My moment came when I realized that, in Fifth Edition terms, there's no mathematical difference between doubling the monsters' hit points and just giving them resistance to all damage. (You might get a rounding issue, but that's minor at best.) The problem is that, not everyone at the table might be min-maxing, and punishing them for the decisions of the other players seemed unfair to me. So at the next session I ran, I basically gave all my monsters an extra ability: "resistance to munchkin damage", where 'munchkin' was defined as 'I think this guy's doing too much damage'.
It worked like a charm -- the fight lasted just long enough to be interesting, and the entire party felt like they were contributing, though they couldn't put their finger on exactly why.
Of course, everyone I talk to immediately wonders how I can be so 'unfair' to the min-maxers at my table, but I think this solution is better than simply providing no fix at all and having boring fights, or punishing everyone by having them all do less effective damage by increasing the monsters' base HP.
I'm going to keep using this system, because it works.
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Pauper