Size Based Falling Creature Damage

[Zhorn]

Some house rules I've had in my notes that I figured I'd post for critique.
Maintaining the 1 die per 10 ft. falling (max of 20 dice) from PHB p183, but with a bit of modifications and additional options for scenarios that have come up in my games.

Fall Damage Dice
Creature size effects the damage die used for fall damage (brought in line with size of Hit Die).


Size
Damage Die
Collision DC


Tiny
d4
DC 5


Small
d6
DC 10


Medium
d8
DC 15


Large
d10
DC 20


Huge
d12
DC 25


Gargantuan
d20
DC 30



Controlled Fall
When you deliberately fall any distance, even as a result of a missed jump, you can choose to use your reaction to try and control your landing. If proficient; make either a Dexterity (Acrobatics) or a Strength (Athletics) check, and deduct the outcome from the fall distance measured in feet for determining damage dice to be rolled. You still end up prone if you take any damage from the fall.

Catching another Creature
You can attempt to catch a falling creature than is the same size category as you or smaller if its fall trajectory is within your character's reach. As a reaction, make Strength (Athletics) check to catch (DC determined by the falling creature's size).
If successful, the number of fall damage dice they need to roll is halved (rounded down), but you are also subjected to damage taken as if the creature fell onto you, even if you don't occupy the same space that the falling creature would occupy.

Falling on another Creature
Creatures that occupy a space that intersects with the trajectory of a falling creature must make a Dexterity saving throw (DC determined by the falling creature's size), taking the same collision damage as the falling creature on a failed save, or half as much on a successful one.
If the falling creature is either of a larger size or only one size category smaller than the impacted creature, then the impacted creature is knocked prone if they fail the save.
Unless the falling creature is caught, this does not change the fall damage taken by the falling creature.

Falling and Diving into Water
When falling into a body of water of sufficient depth (DM fiat), fall damage is ignored for distances of 20 feet or less, and only deals half damage for distances 100 feet or less.
For fall distances of 100 feet of less; as a reaction you can attempt to dive to negate the fall damage. If proficient, make either a Dexterity (Acrobatics) or a Strength (Athletics) check against a DC 10, increasing by 5 for every 20 feet fallen.



Fall Height
Dive DC


Less than 20 ft.
DC 5


20 ft.
DC 10


40 ft.
DC 15


60 ft.
DC 20


80 ft.
DC 25


100 ft.
DC 30

[Yakk]

If you want realism, tiny creatures shouldn't take much if any fall damage. You can drop a mouse or squirrel a mile and it won't even be stunned. 20d4 js way way way too much.

[Zhorn]

If you want realism, tiny creatures shouldn't take much if any fall damage. You can drop a mouse or squirrel a mile and it won't even be stunned. 20d4 js way way way too much.
Less of an attempt to model 100% accurate realism and physics simulation, and more just a tweak in that general direction while trying to maintain simple to implement rules.
Any rule will fall apart under the magnifying glass of realism, and any system can get too complex to use in game if you try to account for every possible variable.
Mice and squirrels are tiny creatures, but so are cats and poisonous snakes, both being bigger and more dense than the former. A flame skulls, demilichs and gazers are also is sized tiny and if you were to negate their flying (hover), that skull should still have a decent chance at taking a cracking on impact.
DM fiat to rule something wouldn't need to roll for fall damage as needed, but I'm not fond of trying to establish rule systems based off the niche exceptions.

[Yakk]

Sure, but why make a complex system that doesn't noticable improve realism?



Size
Fall Increment
Max Fall


Tiny
1d4 per 20'
10d4 at 200'


Small
1d4 per 10'
20d4 at 200'


Medium
1d6 per 10'
20d6 at 200'


Large
1d10 per 10'
20d10 at 200'


Huge
1d12 per 5'
40d12 at 200'


Gargantuan
1d20 per 5'
40d20 at 200'



Cats don't take much damage from long falls either.

Now, damage-per-distance *and* "terminal velocity" should both scale with size, but I got lazy and set terminal velocity to 200' for everyone.

This is still overly harsh to smaller than medium and overly generous to larger than medium creatures.

[Zhorn]

Getting too complex there for my tastes with the different increments and different maximums. Shifts away from an 'easy to know constant' to 'needing a table for reference' which translates to "not going to bother". Ease of use should always be a priority.
I'm sure there's going to be someone who'll look at your suggestions and want to lean even further in with different weights or variances within the size categories
"Well clearly iron golems and gorgons would weigh far more than horses, so they should deal more falling damage. And giant eagles being avian would suggest hollow bones, that means they'd be lighter and deal less damage when falling.".

[Yakk]

Good point, it is too complex.

Tiny: All tiny creature are immune to falling damage.
Small: All small creatures have resistance to falling damage.
Large and bigger: All creature Large or bigger have vulnerability to falling damage.

Much simpler. And yes, a cat is closer to immune to falling damage than they are to taking 1d4 per 10'.

[Zhorn]

Which is still a list of exceptions and special conditions.
I get what you are looking at, I just don't agree with the reasoning for establishing blanket damage immunity/resistance/vulnerability. falls =/= controlled landing, and even in controlled landings, and injuries still occur and regularly do. And again, not all tiny creatures are as light as mice, or have righting-reflexes like cats, those are special niche exceptions.

I do encourage you to have your own fall damage rules, but for the purposes of critiquing what I have here, the underlying thing you are picking at is the baseline PHB ruling of 1 die per 10 feet and the dice cap, not my houserules.