Balancing the chance to be awesome versus the chance to suck

[Raineh Daze]

All of those scenarios seem utterly ridiculous, given that we're talking about a centuries old beast that's something like fifty feet long and should not have any chance of failure in disembowelling a random farmer. Something with +44 to attack and +33 natural armour shouldn't be able to miss or get hurt when attacking a peasant.

[Kasz]

Seems quite unlikely that a commoner / farmer would wander into an Ancient Red Dragon's den... more unlikely than a 0.025% chance by far.

[Raineh Daze]

Ancient Red Dragons have to eat, you know. People might not be the best choice, but they breed like rabbits and are easy to catch. Also, they might have shinies.

[oslecamo]

How do you think all those orphans with tragic stories on how their whole family got killed by a big monster survived to tell the tale?

[veekie]

A 1/400 chance that something like an ancient red dragon would miss a commoner and hurt itself is simply ludicrous, though. :/

Depends a lot on the degree and nature of self hurt. Most critical tables(whether failure or success) goes to the extreme of abandoning sense entirely, and inflicts comedic, not plot advancing complications.

Consider for example, a lion attacking a gazelle. Most of the time, the gazelle gets killed without fuss, and the lion gets fed. Sometimes the lion lands badly, causing a sprain or scratches itself against a rock. Very much like the dragon vs commoner situation, the gazelle rarely survives the second pass(though if it does, there is a healthy chance of running away successfully), and the lion will heal the scratch or sprain in a few days at worst.

What there shouldn't be is a total reversal of the situation. You can basically break any challenge down into 5 degrees:
-Certain victory
-Likely victory
-Close contest
-Likely defeat
-Certain defeat
The role of luck there, moves you up or down the scale but one step. It should most definitely not flip the outcome entirely. Dragon chips a fang on commoner yes. Dragon decapitates himself on commoner's fist, no.

[Raineh Daze]

Because the dragon was full, obviously. :3

Consider for example, a lion attacking a gazelle. Most of the time, the gazelle gets killed without fuss, and the lion gets fed. Sometimes the lion lands badly, causing a sprain or scratches itself against a rock. Very much like the dragon vs commoner situation, the gazelle rarely survives the second pass(though if it does, there is a healthy chance of running away successfully), and the lion will heal the scratch or sprain in a few days at worst.

Spot the difference between the two scenarios. I think it might have something to do with ability scores. What sort of dragon, with the ability to eviscerate an army without serious harm and outthink almost all generals, would fail to hurt a commoner like that?

[oslecamo]

Overconfidence obviously. Since it's "just a commoner", the dragon's much likier to slouch off when diving in and hiting some rock or something instead of the relatively tiny humanoid trying to hide in the nearest crevice.

[Raineh Daze]

... reading through the rules, I must question what use most dragons are going to have with DR/Magic, seeing their HD and the fact it doesn't protect them against random pieces of scenery.

[veekie]

Replace the gazelle with a rabbit and you have again, the same scale. The factor of chance does not matter in the overall contest.
The commoner still has zero chance of defeating the dragon. So the dragon's first flyby didn't kill him. The second one will. Or the third. The commoner cannot even inflict 5% of the dragon's hp in damage if he hit 3 times and double 20s critted on each exchange, assuming he could beat the DR. Each time the dragon misses, the commoner has lived for 6 more seconds at best.

So lets say the commoner rolls nothing but 20s and the dragon rolls nothing but 1s for 1 minute.
First round, the dragon just does it's usual swoop and grab. He grabs a fistful of dirt instead. The commoner might run(provoking an AoO, which also misses because of nat 1) or attack(inflicting a maximum of 10 damage out of 660 hp, and somehow ignoring DR).
Second round, the confused dragon performs a full attack, 6 attacks, which all miss somehow. The commoner goes for another 10 damage, he's feeling lucky.
Third round, fed up, the dragon loses it, using not a single spell, it attacks with the breath(automatically killing the commoner despite the successful save), crush(automatically killing as well) or tail sweep(also an auto kill).

Odds involved by now? Ignoring the commoner's attack rolls, the dragon has rolled 7 1s in a row, which is a 1/1,280,000,000 chance. I believe getting hit by a meteor is more likely.

[zugschef]

A pro skateboarder is a specialist, most of them have been doing it for over a decade, since they were very young... then why do we get the bloopers/crashes reel at the end? because occasionally they do everything right and get unlucky, or they make a minor error.

that's the wrong perspective. they sometimes fail at complicated tricks but they don't when doing something basic. with auto-fail on a 1, they would.

[Kasz]

Just because the scenery does 1d6 damage to the dragon doesn't mean it gets past the DR... a Dragon might be more careless knowing that if he steps on a sharp spike it never hurts (or gets past DR) or that when he crashes through some rocks and receives some bludgeoning damage that he never actually loses hp, the rocks bounce harmlessly off his hide, it's just inconvenient because it stops his momentum.

Reasonable fumbles are the main issue most people have... it's not exactly unfair to say if you attack a training dummy 400 times you might slip and lose your footing or drop your sword or fall over backwards. Maybe even drop the sword on your foot and get a slight cut. Some DMs see this as an opportunity to say "Oh you fumbled? Roll on the fumble chart WOO YOU CUT YOUR OWN HEAD OFF!"

Make the fumble reasonable to the fail... Fumbled an attack roll... lose some AC or an action picking yourself up. Fumbled throwing a lit keg of gunpowder.... yeah you might be in for some damage dice.

A pro skateboarder is a specialist, most of them have been doing it for over a decade, since they were very young... then why do we get the bloopers/crashes reel at the end? because occasionally they do everything right and get unlucky, or they make a minor error.

that's the wrong perspective. they sometimes fail at complicated tricks but they don't when doing something basic. with auto-fail on a 1, they would.

I'd like to see a skateboarder do 400 kickflips in a row without failing one.

Disclaimer; I've already explained I use a confirmation roll for fumbles, yeah 5% autofail is too damn high.

[Raineh Daze]

A creature with this special quality ignores damage from most weapons and natural attacks. Wounds heal immediately, or the weapon bounces off harmlessly (in either case, the opponent knows the attack was ineffective). The creature takes normal damage from energy attacks (even nonmagical ones), spells, spell-like abilities, and supernatural abilities. A certain kind of weapon can sometimes damage the creature normally, as noted below.

Unfortunately, RAW specifies that a dragon would indeed be able to wound itself on a sharp bit of rock.

[Kasz]

A creature with this special quality ignores damage from most weapons and natural attacks. Wounds heal immediately, or the weapon bounces off harmlessly (in either case, the opponent knows the attack was ineffective). The creature takes normal damage from energy attacks (even nonmagical ones), spells, spell-like abilities, and supernatural abilities. A certain kind of weapon can sometimes damage the creature normally, as noted below.

Unfortunately, RAW specifies that a dragon would indeed be able to wound itself on a sharp bit of rock.

Surely a sharp or heavy rock is closer to a natural attack or weapon attack.
It's Slashing or Bludgeoning... That's not an Energy Attack, a spell, a spell-like or a supernatural ability.

[Raineh Daze]

It's not attached to a creature or anything, so it's hardly a natural attack, and it's neither wielded nor manufactured in any way. Therefore, it is neither a weapon nor a natural attack. Same problem with DR and falling damage.

[RogerWilco]

To answer one of the original questions:

When we started playing (A)D&D many years ago, one of the first things that happened was a TPK because nobody rolled above 5 for an entire encounter. Our group still has a fear of Fire Beetles 15 years later.

After that we learned that sometimes the DM needs to fudge the dice or have some deus ex machina save things. Having a TPK from a low level random encounter shouldn't be part of the system from my point of view.