D&D 5E Would you change a monster's hit points mid-fight?

[the Jester]

Occasionally I will; not often. I really do prefer to let the dice fall where they may, but once in a while, if it's a foregone conclusion and there's no point to playing it out...

 

[JWO]

Is it arbitrary, and are the players unaware of it?

Knowing a monster's hit points isn't something that the players should know about. Even if they've slavishly learned every detail of the Monster Manual, that's something the DM should be able to switch up anyway. Using the knowledge they've gained from the Monster Manual is metagame thinking.

I do believe that most of the numbers in the books are pretty arbitrary. Of course, there's an internal logic that they follow for the most part so in that sense they're not 100% arbitrary but they're still just numbers that game designers have used to represent the fictional parameters of a fictional world. If the DM wants to change one of those numbers to make the game 'better' (whatever that might mean), then I don't see that as a problem.

 

[The Grassy Gnoll]

This may be off-topic, but there's a 'rule' of improvisational acting, usually the 'first rule of improv club', that says: "always say yes - embrace it". The 'second rule of improv club' is: "add something".
These are rules that allow crazy outcomes to work in unexpected ways. Similarly so for RPGs, especially for the random element of the dice.
So, the dice hate the PCs in combat. Everything is a swing and a miss, or worse, a fumble. Meanwhile, the monsters have had their Ready Brek today and everything is hitting and doing top damage. The first rule says, "yep, they're toast if they keep this up". The second rule (essentially failing forward) says "the monsters drive you back towards the wall, where the sleeping pallets have been upended during the fight...they're big enough to duck behind and good for half cover", or "the fighter is knocked prone but from his floor level view he sees that the lead three monsters are all stood on a rough carpet, which is just within reach for him to try to yank them off balance".
Alternatively, Boss Monster appears, war axe in hand, twenty stone of solid muscle wearing a necklace of adventurers testicles, designed to really test the heroes to the max. The PCs take him out in round one. Indiana Jones moment! The first rule says, "yep...he's toast. Dang", the second rule says "he falls dead with a thud, his huge bulk splintering one of the pillars holding up the Temple...as you grin at one another in celebration, the ceiling starts to shake and collapse as the pillar cracks and falls...make a DEX check to avoid falling masonry".
Recent example - the players were on their last legs, and a desperately cast Thunderwave spell took out all but one bad guy, who made his save and only took half damage. One more hit and two of three characters were down. Bad guy had two attacks... First rule said, "yep, it's his turn now too". So I judged (second rule, add something) that all the coins on the table (they had been gambling), and the table itself were also hurled at bad guy due to the spell, doing a further bit of damage...the die I told the PC to roll providing just enough to take him out. Fudging maybe but in a different way to just adjusting the HPs. Also the image of having to pull the silver pieces out of his face if they wanted all the treasure was a memorable one and prompted some nice RP.
It's basically embracing the dice as they are but giving the PCs options to avert defeat or consequences to ensure they are challenged - failing forward/succeeding sideways.

 

[The Human Target]

This may be off-topic, but there's a 'rule' of improvisational acting, usually the 'first rule of improv club', that says: "always say yes - embrace it". The 'second rule of improv club' is: "add something".
These are rules that allow crazy outcomes to work in unexpected ways. Similarly so for RPGs, especially for the random element of the dice.

Here's the thing. You deciding the monsters are standing on a rug to pull and alerting the player without them asking is just as "fudgy" as just making the fight easier mechanically.

Though I like the creative city of it.

 

[JWO]

This may be off-topic, but there's a 'rule' of improvisational acting, usually the 'first rule of improv club', that says: "always say yes - embrace it". The 'second rule of improv club' is: "add something".
These are rules that allow crazy outcomes to work in unexpected ways. Similarly so for RPGs, especially for the random element of the dice.
So, the dice hate the PCs in combat. Everything is a swing and a miss, or worse, a fumble. Meanwhile, the monsters have had their Ready Brek today and everything is hitting and doing top damage. The first rule says, "yep, they're toast if they keep this up". The second rule (essentially failing forward) says "the monsters drive you back towards the wall, where the sleeping pallets have been upended during the fight...they're big enough to duck behind and good for half cover", or "the fighter is knocked prone but from his floor level view he sees that the lead three monsters are all stood on a rough carpet, which is just within reach for him to try to yank them off balance".
Alternatively, Boss Monster appears, war axe in hand, twenty stone of solid muscle wearing a necklace of adventurers testicles, designed to really test the heroes to the max. The PCs take him out in round one. Indiana Jones moment! The first rule says, "yep...he's toast. Dang", the second rule says "he falls dead with a thud, his huge bulk splintering one of the pillars holding up the Temple...as you grin at one another in celebration, the ceiling starts to shake and collapse as the pillar cracks and falls...make a DEX check to avoid falling masonry".
Recent example - the players were on their last legs, and a desperately cast Thunderwave spell took out all but one bad guy, who made his save and only took half damage. One more hit and two of three characters were down. Bad guy had two attacks... First rule said, "yep, it's his turn now too". So I judged (second rule, add something) that all the coins on the table (they had been gambling), and the table itself were also hurled at bad guy due to the spell, doing a further bit of damage...the die I told the PC to roll providing just enough to take him out. Fudging maybe but in a different way to just adjusting the HPs. Also the image of having to pull the silver pieces out of his face if they wanted all the treasure was a memorable one and prompted some nice RP.
It's basically embracing the dice as they are but giving the PCs options to avert defeat or consequences to ensure they are challenged - failing forward/succeeding sideways.

Hmm...well that's a nice alternate way of looking at it!

 

[FormerlyHemlock]

I'm curious, does your DM tell you the exact target DC for an ability check?

I haven't run or played a campaign (any edition) where the DM would share numbers. The player could ask how challenging their character might find a task, and the DM would respond anywhere from impossible to trivial, but wouldn't give a concrete number. It would require highly similar traps and very similar dice rolls for a player to suss out the DC of a trap.

No, not usually, but he does have us make our own rolls, and I'm pretty observant[1]. For the sake of the forum I simplified my hypothetical mental statement from a neural net of inferences and deductions to a single number. Don't read too much into that number.

[1] For example, I'll notice if the DM tends to assign DCs in multiples of five when he does tell us the exact DC. (DC 10 to climb a tree in combat, f'rex. Not DC 8 or DC 11.)

 

[ExploderWizard]

Occasionally I will; not often. I really do prefer to let the dice fall where they may, but once in a while, if it's a foregone conclusion and there's no point to playing it out...

Those are the kinds of situations where I will decide that morale is broken and the NPC or monster either tries to flee, offers to surrender and hints that it could be useful, or just blubbers and pleads for its life depending on the nature of the creature in question. To me that adds more opportunity for interaction and role play than just reducing the HP pool.

 

[The Human Target]

Fudging and creating content on the fly are different things. Spontaneous creation of NPCs or even entire areas when the PCs wander off the edge of the map is simply world building done on the fly. Changing the results of die rolls to suit a desired outcome isn't creating any content, its simply an erosion of the integrity of the game.

From my perspective, the game is much more interesting if both the players and the DM discover the results of play together. Unexpected decisions made by the players combined with the randomness of a die roll make the experience less predictable and thus more interesting.

By this I don't mean that every detail is random. It would be hard to maintain a consistent world in those circumstances. My point is that when the dice are used to determine something, I like to abide by the result. The whole point of dice is that the result is random and can take the game in unexpected directions. Disregarding results you do not like means that the dice shouldn't have been rolled in the first place. The stakes and the odds on many rolls, can be determined beforehand. If there is a consequence that you cannot bear as a result of a die roll then don't include it.

The problem being that dice are random, and can skew in weird directions. That randomness can result in things just not being interesting.

I don't want the DM to be Judge Dredd, allowing no nuance or interpretation. Making no decisions, just sterile rulings based solely on the Law of the Dice.

If that was the case, DMing wouldn't really be necessary. Everyone could just play by reading through pregen adventures and letting the rules and rolls determine everything.

A DM is more than a rules Lawyer and random NPC name generator.

 

[The Grassy Gnoll]

Fudging is fudging, I suppose. Yeah. I just go about it a different way.
Ultimately, while the players, for many reasons (bad rolls, bad decisions), may find themselves up Sh*t Creek, it's the DM's job to give them a paddle.

You can of course beat them with it a little, too.

 

[FormerlyHemlock]

Knowing a monster's hit points isn't something that the players should know about. Even if they've slavishly learned every detail of the Monster Manual, that's something the DM should be able to switch up anyway. Using the knowledge they've gained from the Monster Manual is metagame thinking.

Metagaming is bad for PCs, because the PCs don't have access to that knowledge. Metagaming is fine for players. If a player says, "Hey, I'm going to cast Hypnotic Pattern at these undead, but I already know it will be useless because my last character discovered that undead are immune to enchantments, so let's not even roll the dice, I'll just scratch off my spell slot and let's move on," that's metagaming but it's not in any way bad.

Consequently, if the player is aware that all the other ogres took 60+ HP before dying, and those last two ogres died just from getting hit with 25 HP of critical damage, it may spoil the player's enjoyment (or not) but either way the PC isn't involved in the metagaming.

TLDR; players having feelings and opinions is part of the metagame, but is also perfectly valid.