D&D 5E Falling Rules and actually Falling

[Tormyr]

Well, no, because you're forgetting the effect on the standard deviation. 20d6 does have an average of 70, with an SD of 7.6. This means 95% of all results will be between 55 and 85.

20d6 exploding on a 6 has, as you note an average of 84, but has an SD of 14.6, meaning it's 95% probability is from 55 to 113.

The probability density function of exploding d6's skews heavily upward, but has a higher variance. It's bottom is still rooted at the same point as non-exploding d6's, but its upper end is much higher than a simple look at the mean would suggest. In fact, the mean of the exploding function is right at the upper 95% boundary for straight 20d6, meaning that, on average, you're at least 50% likely to roll better than the upper 2.5% likelihood on straight 20d6.

And this same pattern holds across all xd6.

The upshot here is that you have a better than 14% chance on 20d6 exploding to roll over 100 damage, and a much less than 1% chance to do so on straight 20d6. You also have an almost 2% chance on exploding 20d6 to exceed the maximum value of straight 20d6.

So, statistically speaking, the chance of better damage is much higher than the means would predict.

While true, it still ends up with the average damage being in the 80s. I just rolled 20 times on Roll20 rolling. The results were (96+95+102+96+110+73+70+126+69+83+76+82+102+79+111+78+75+83+99+66)/20
= 88.55

9 rolls were above average with a couple really high damage rolls compared to normal 20d6.
3 rolls were at or below average for normal 20d6.
8 were between the averages for 20d6 and 20d6!.

This is definitely the simplest solution for additional fall damage and what I would recommend for someone who wants a rules light solution. It has the possibility that a 10' fall will kill a level 1 character outright; falls have a chance of doing catastrophic damage once in a while; and it still integrates with the fall damage mitigation features from some of the classes.

 

[Tormyr]

For sticking a landing after a long fall that seems like a dex save? Once you’re beyond your safe tier make a dex save to halve the damage, difficulty determined by the type of surface you’re landing on. Relatively clear and level? DC 10. Uneven terrain with some rocks to avoid? DC 15. Hazardous terrain, stalagmites, crystal shards, spikes? DC 20(+).

Otherwise I like the idea. Cool

Part of the reason I decided to use a Dexterity (Acrobatics) check for the reaction is that all classes have the option of choosing to have proficiency in it vs proficiency in Dexterity saving throws, and some classes can get expertise. It isn't a very 5e way of doing things, but having the Acrobatics check result subtract from the fall damage then means that someone who has a result of 0 damage sticks their landing.

As for terrain problems, difficult or particularly solid terrain can impose disadvantage on the role. Purposely making the jump gives advantage on the role. So those could cancel each other out. As an example from last night's game: Everyone was pulling themselves out of a 30' spiked pit trap. The ranger made her DC 10 Strength (Athletics) check to climb out via rope and grappling hook, but the rogue and bard failed. I had them fall from a distance of 10' which is 10 damage in my rules. They each used their reactions to make Dexterity (Acrobatics) checks to mitigate the 10 fall damage. The rogue rolled a 10 or better mitigating all fall damage, but the bard only rolled an 8 and took 2 fall damage in the end. Here is how it was narrated:

Me: The ranger climbs her way out. Unfortunately the rogue loses his grip halfway up and takes out the bard on the way down. The bard lands prone, and the rogue stumbles forward but keeps his feet.

Rogue: Cool!

Bard: Eh, 2 damage is not too bad.

Me: Unfortunately, you both hit the spikes at the bottom of the trap again. You take...

 

[Tormyr]

What about reactions (if 499 feet or less) such as Feather Fall, are those still permitted?

[MENTION=5590]jodyjohnson[/MENTION] talks about acting in initiative in the next sentence for 500+' falls. The reason that I handle it that way is it is how far a 6' human falls in 6 seconds. After that, the person falls roughly 1000' every six seconds thereafter. So feather fall still works as intended for someone falling in the first round. The difficulty is that it cannot be effectively used at the beginning of a 1000' fall. The spell only lasts for 1 minute and limits fall distance to 60' every round (6 seconds) or 10' / sec. That means it only works for 600'.

 

[Tormyr]

Just a side commentary of the frequency of the 1000' foot fall. I've been listening to a lot of Dice, Camera, Action and Critical Role and the 1000' foot fall seems to come up really often.

Partly because it allows the characters to act before the fall meets it's end. 499 foot fall - no chance to officially act. 500+ chance to Act in initiative order. And then it is totally hilarious to have a character take 100d6 falling damage (no cap at 20d6) especially if you haven't announced that particular house rule.

I think normally we've gravitate towards 100' falls but we all know 10d6 isn't killing anyone after level 3.

I haven't watched DCA, but I can only think of a few times long falls have come into play in Critical Role and my own games.

I do know they have given falls and jumps much more respect now. When a 100' fall does 61 damage instead of 35, they seriously consider other ways down first.

Having these rules in place would have helped me in my Age of Worms campaign. The ~17th level party visited a city carved into the side of a cliff. The valley floor was 1,500 feet below. At one point, they were fighting an ancient green dragon. The wizard used wish to turn into an adult red dragon, and the bard knocked the green dragon out with tidal wave which carried it off the cliff. Not realizing the green dragon was unconscious the red dragon dove after the green dragon to make sure it did not escape. Meanwhile, the dwarf paladin got knocked over the edge as well. At the time I ruled that everyone fell at a rate of 200' / round as that matched the maximum damage dice. The paladin had plenty of rounds to heal himself before contemplating the end, and the wizard could not catch up to the plummeting red dragon. In the end, the sorcerer used teleport to save the paladin at the last second by using his draconic wings to pull out of a dive while the dwarf cast reduce on himself to make himself lighter. Meanwhile the wizard only managed to hit the green dragon once on the way down with his flame breath before the ground added another death saving throw failure. The wizard tried to pull up, but he failed a Strength check. His wings popped upward like an inverted umbrella as he tried to pull up from his dive, and he crashed through the green dragon. The impact gave the third death saving throw failure, the green dragon body burst open, and enough damage was done to knock the wizard out of his dragon form. He got up from the crater his dragon form had left amid the pieces of green dragon.

Where the new rules would have helped, is that it would be codified that everyone had one turn to act in initiative before the falls were resolved. The wizard would not have been able to catch up to the green dragon, the 348 damage from the fall would not outright kill the green dragon whose max hp was 355. The green dragon would have had a few turns to try to roll 20 on a death saving throw and use its ring of invisibility to escape. The sorcerer would only have had 1 turn to teleport to the paladin. He honestly probably would not have made it in time, but the paladin had enough hp to not be killed outright. The sorcerer could have teleported to the paladin and administered a potion of healing.

 

[snickersnax]

Secondly, another way to look at this is that there is nothing wrong with falling damage. The problem is with the hit point system.

IRL lethal falling distances are consistently 48 feet for LD50, meaning 50 % of the people who fall 48 feet die.

This would suggest that 1st level hit points are too low and level 20 hit points are too high.

 

[Stalker0]

IRL lethal falling distances are consistently 48 feet for LD50, meaning 50 % of the people who fall 48 feet die.

So 50% of the population will survive a 5 story drop? Man, I was overestimating gravity apparently.

 

[Horwath]

How about every 10ft you suffer 20% of your max HP in damage.

That way 50ft drop will get you to 0 HP and 100ft drop will kill you in every scenario.

 

[Ovinomancer]

So 50% of the population will survive a 5 story drop? Man, I was overestimating gravity apparently.

Pretty sure that's dead right there on landing and not dead on complications from landing a little while later.

 

[snickersnax]

How about every 10ft you suffer 20% of your max HP in damage.

That way 50ft drop will get you to 0 HP and 100ft drop will kill you in every scenario.

Also the LD90 is 84 feet...

 

[snickersnax]

Pretty sure that's dead right there on landing and not dead on complications from landing a little while later.

Usually the data is reported as overall survival so that would include complications...

Here is an example of the kind of studies out there: https://www.ncbi.nlm.nih.gov/pubmed/3735467

They reported 84% actual survival from 5-7 stories despite having a 50% survival prediction based on the Injury Survival Score. These were patients who actually made it to a hospital, so there may have been others that just outright died on impact as you suggest.