How many hp in a block of stone? And what is its falling damage?

[Cheiromancer]

How many hit points does a 10-ft. cube of stone have? How does this scale for larger shapes?

I'm sure this involves construct bonus hit points and VSCs somehow, but I don't recall the details.

Also- how much damage does a block do when it falls on someone? Or when it is gently lowered on someone. I remember there being some controversy over this, but I don't recall how it turned out.

[edit]I have a 10-ft. cube of stone weighing about 30 tons (62 thousand pounds). Does that sound about right? In which case it would count as a a Gargantuan creature, and should get a construct hit point bonus of 80 (the MM says 60, but the golems in the Bestiary use a different convention). So 80 hp for a 10-ft. block of stone? A 20-ft. block would have 120 hp, a 40-ft. block would have 160 hp, and so on.

Unless I've totally misunderstood something.

Hmm. The earth weighs 5.97 x 10^24 kilograms, which is 6.5 x 10^21 tons. I get... 193 thousand hit points for the earth?

[edit] That was with logarithms. Using UK's tables it is more like 160 000 hit points.

i.e. 10 size categories is a billion-fold increase, so the earth is 20 size categories more than a 6.5 kilo-ton object which is Titanic, and has 160 hp. Every two size categories doubles the construct bonus, so that's 10 doublings; about 1000 times as much.

But I see in another thread that the earth should have only about 100,000 hit points. And the moon, which weighs 1/81 as much, should have around 60,000. It should be a little less than half the hit points of the earth, if calculated in this way; reducing the weight by 64 should halve the hit points.

Hmmm. Close enough. I think.

 

[Cheiromancer]

Looking at the Dungeons section of the SRD, it says a 10 foot section of 5-ft. thick unworked stone is 900 hp. Presumably a 10-ft cube is 1800 hp. But comparing this with the Wall of Stone spell suggests that they meant a 5-ft. cube. Or maybe a wall of stone is just tougher. Anyway, there is a considerable discrepancy!

The earth would have about 7 billion hit points if you follow the WotC rules. (8000 miles x 5000 ft. in a mile x 12 inches in a foot x 15 hp per inch)

 

[CRGreathouse]

The earth would have about 7 billion hit points if you follow the WotC rules. (8000 miles x 5000 ft. in a mile x 12 inches in a foot x 15 hp per inch)

69.8 sextillion hit points (~7e22) if you use cubic feet instead (unworked stone, not wall of stone).

 

[Upper_Krust]

Hiya matey!

How many hit points does a 10-ft. cube of stone have?

60 hp with hardness between about 5-8 depending on how hard the stone is.

Or possibly 80 hp, I'm not sure if I changed that for the bestiary.

How does this scale for larger shapes?

Staggered double.

I'm sure this involves construct bonus hit points and VSCs somehow, but I don't recall the details.

Also- how much damage does a block do when it falls on someone? Or when it is gently lowered on someone. I remember there being some controversy over this, but I don't recall how it turned out.

Well Crush is +3 VSCs above slam. You also take into account the mass (which size category) and density (as per VSCs).

So a Gargantuan stone block (+7 VSCs?) would deal 8d6 damage (off the top of my head).

[edit]I have a 10-ft. cube of stone weighing about 30 tons (62 thousand pounds). Does that sound about right? In which case it would count as a a Gargantuan creature, and should get a construct hit point bonus of 80 (the MM says 60, but the golems in the Bestiary use a different convention). So 80 hp for a 10-ft. block of stone? A 20-ft. block would have 120 hp, a 40-ft. block would have 160 hp, and so on.

Unless I've totally misunderstood something.

Hmm. The earth weighs 5.97 x 10^24 kilograms, which is 6.5 x 10^21 tons. I get... 193 thousand hit points for the earth?

[edit] That was with logarithms. Using UK's tables it is more like 160 000 hit points.

i.e. 10 size categories is a billion-fold increase, so the earth is 20 size categories more than a 6.5 kilo-ton object which is Titanic, and has 160 hp. Every two size categories doubles the construct bonus, so that's 10 doublings; about 1000 times as much.

But I see in another thread that the earth should have only about 100,000 hit points. And the moon, which weighs 1/81 as much, should have around 60,000. It should be a little less than half the hit points of the earth, if calculated in this way; reducing the weight by 64 should halve the hit points.

Hmmm. Close enough. I think.

Well its possible I was one category out from the start (I thought Gargantuan was 60 hp added to a construct, but if I have changed it in the Bestiary then my initial calculations could be one VSC out).

Secondly, its been a while since I worked this out (pre-bestiary in fact) and its possible I may have forgot to calculate the additional size category that would take effect because the object is spherical (or roughly equal on all sides*)

*That would give a natural creature 1 HD per foot, rather than 1/2 HD per foot for a humanoid. So thats a doubling of HD - effectively an increase of +1 VSC.

So I can see how you could work it out as 160,000 hp. Double my original 80,000.

With regards your 193,000 calculation I think I may have been using a slightly lighter tonnage per square metre of the Earth. I think I was using 4.5 or 5 tons/sq. metre

 

[Cheiromancer]

@CRGReathouse: Good point!

7 billion hit points would punch a hole straight through the earth, but it would only be a 10-ft. tunnel; the bulk of the earth would be unaffected. You'd need to do 10 trillion times as much damage to destroy the whole thing.

Would it be a reasonable addition to the rules that if you punch through a barrier you affect an area as wide and deep as the distance penetrated? That would bring the earth back to 7 billion hit points if done at one blow.

What did your investigations into falling/crushing damage turn up?

 

[Buugipopuu]

My reasoning (which treats objects the same as creatures, even if most of their stats are 0):

When you have something drop on you, it's like being Crushed by it. Since you don't need any kind of skill to crush things, nonproficiency or the object not being designed as a weapon shouldn't matter. This means that Crush attacks by objects that are designed as weapons probably deal extra damage, although they could get Improved Natural Weapon as a bonus feat.

Increasing the fall height by a factor of 64 increases the damage by a factor of 2. This means increasing the fall height by a factor of about 12 increases the damage by a factor of 1.5. To make things simple: Every factor of 8 increase in fall distance (over 5 feet) results in an increase in damage by one VSC.

Terminal velocity: For two objects of identical shape, Terminal Velocity varies with the square root of density. This means that for every VSC possessed by the falling object, its terminal velocity increases by a factor of 8. This handily means that for every VSC possessed, it can gain a maximum of 1 more from falling. Being extremely crude here, let's assume that the base terminal velocity is 2 VSCs, reached after falling 320ft.

Especially aerodynamic objects can gain up to 2 free terminal velocity VSCs from their shape, while very unaerodynamic ones can lose up to 2. If these are important, they should be noted in the creature's entry. Similarly, high or low density atmospheres can change the maximum effective falling distance. In high or low gravity situations, simply multiply the distance fallen (or the maximum effective falling distance, if reached) by the number of times the gravity exceeds 1g.

Summary:

Normal creatures (and objects), deal normal damage with Crush if they are simply trying to crush from the ground. They gain additional Size Categories worth of damage for falling long distances, up to a maximum of 2+number of VSCs possessed.

Now: A 10ft cube of stone is a large object that due to its high volumetric efficiency and density has 2 Virtual Size Categories This means that its base falling damage is 4d8. After falling 40ft or more, this increases to 8d6, and after falling 320ft or more it deals 8d8. It can continue falling further to gain extra damage until it has fallen 20,480ft, where it will deal 15d10 damage.

These damages should be used as both damage dealt by falling objects and damage dealt to falling objects. Skill checks that reduce the effective distance of a fall only reduce it for the falling creature, not anything it lands on.

A second example:

From the first Immortals session I ran, a Grease spell and a failed Balance check by an Orichalcum Guardian lead to it falling a rather long way (about 14 miles in fact, since it fell through a Gate with the other end positioned high above the ground). It has 15 VSCs, and so has a maximum effective falling distance of A Very Long Way. Air resistance basically has no effect on the damage it takes. 14 miles means it gains 6 additional size categories due to its speed, and deals 1,920d10 damage to the ground, and itself (Golems have very bad Jump and Tumble scores). This averages to 10,560 damage, which was in fact sufficient to destroy the Guardian, as it had already taken a small quantity of damage, and Hardness 100 is not significant against that sort of threat. The energy released by dropping one and a quarter million tons of Guardian fourteen miles onto a solid surface is equivalent to the detonation of 750 Gigatons of TNT.

 

[Ltheb Silverfrond]

I like this math; It is more realistic than just plain mesuring X denomniations of 5', and scales well. The only "hole" I found in your example: Blocks and things are entirely the thing trying to crush you, so they should deal damage at +3 VSCs, not 2.

Yes, theres a reason Bowser in the Mario games fills his castle with Thwomps. They hurt.

Perhaps a simpler method of determining Terminal Velocity should be used; the less times one needs to find the square root of something, the better. While the mechanics should stay the same, I think it would be best if it were a tad easier to figure out. Pulling out a calculator in the middle of the game (unless you allready have one on hand) or doing extreme ammounts of math really slows things down.

Other than that, It looks great.

 

[Buugipopuu]

You don't need to work out the terminal velocity to get the damage, only the distance after which it is reached. Since Size is all logarithmic, the only thing you need to do is addition.

Crush damage seems to be already using the creature's entire body, according to the Epic Bestiary page 6, and doesn't get any extra damage on top of that.

Distance  Bonus VSCs  Natural VSCs needed
5'           0                0
40'          +1               0
320'         +2               0
2560'        +3               1
20480'       +4               2
ect

It occurs to me that these rules could be used for ramming things (use the creature's Fly speed as its Max. Effective Speed) and jumping on them, although those are very risky forms of attack. If I were writing a book I'd throw in some feats to reduce the damage dealt to the rammer/jumper. Obviously if you took Improved Natural Weapon (Crush) you could choose not to apply it to the damage you dealt to yourself, but there should probably be Improved Jump Attack and Improved Ram feat/ability trees that further reduce it. This gets silly if you got rammed by a Superluminal creature (There's no Relativity in D&D, thankfully), but they'd almost certainly destroy themselves in the process. Unless you were to rule that all the Divinely enhanced speeds used some form of mass lightening magic or supernatural effect, and only natural speed could do damage, which would prevent possible exploits.

While pointless, it might even be possible to derive damage for arrows and suchlike by assuming they're Diminutive objects Ramming their target very quickly.

 

[Cheiromancer]

The energy released by dropping one and a quarter million tons of Guardian fourteen miles onto a solid surface is equivalent to the detonation of 750 Gigatons of TNT.

The math works out to be about 100 kilotons. If it fell 14 miles (about 21,000 metres) in an earth-like gravity well, it take about a minute to hit the ground and would be going a bit less than half a mile a second when it hit. It would have an energy of about 500 tera-joules, which according to this is about 100 kilotons.

I wonder how the damage of nuclear explosions was calibrated? It would be neat if the numbers for falling objects could be reconciled with the energy yield of atomic bombs.

 

[Ltheb Silverfrond]

...
It occurs to me that these rules could be used for ramming things (use the creature's Fly speed as its Max. Effective Speed) and jumping on them, although those are very risky forms of attack. If I were writing a book I'd throw in some feats to reduce the damage dealt to the rammer/jumper. Obviously if you took Improved Natural Weapon (Crush) you could choose not to apply it to the damage you dealt to yourself, but there should probably be Improved Jump Attack and Improved Ram feat/ability trees that further reduce it. This gets silly if you got rammed by a Superluminal creature (There's no Relativity in D&D, thankfully), but they'd almost certainly destroy themselves in the process. Unless you were to rule that all the Divinely enhanced speeds used some form of mass lightening magic or supernatural effect, and only natural speed could do damage, which would prevent possible exploits...

Well, since the only thing that can travel at the speed of light, usually, is Light, I would say when you move so fast, you effectively "become" light, and could not ram anything very well. I am sure if you found the "density" of a light particle/wave, you could figure out how much damage A Neutronium Golem deals when the resident Time Lord decides to play "Pinball" with your galaxy.