Rules for many Flasks of Alchemist’s Fire "detonating" at once

[Red Bear]

If there are 50 flasks of Alchemist's fire in a 5 feet sided cube and a player casts shatter (or he breaks them all at once in any other way). What do you think the effect should be? How much damage should it do? How large the effect should be?

Bonus question: Is there a real world substance that catches on fire when exposed to air like Alchemist's fire does? What happens if you break 50 flask of this substance at once?

[Spore]

Some force gets lost, and with that amount of glass vials, I'd say piercing damage becomes a major factor.

I would half or third the fire damage und give the splash area 2w6 piercing damage.

[Squark]

Whooboy, bringing physics into D&D. [Insert catgirl killing jokes here]


Hmm... Well, I think this depends on a lot of things. Are we talking 50 vials in a sack? A sturdy box that would put the explosion under pressure?

From a rules perspective, I know Saga Edition had rules for using multiple sticks of detonite (plastic explosives). Perhaps you could borrow those (can't remember for the life of me what those were)

[Worira]

Alchemist's fire doesn't explode, it burns.

[jindra34]

It does regular splash damage x50. And since its not being thrown at someone not much else.

[Fouredged Sword]

Normal splash damage X 50, so more like termite than gas.

[Spore]

Whooboy, bringing physics into D&D. [Insert catgirl killing jokes here]

I really just needed a reason to NOT give a character the capability to deal 50d6 damage on that square equalling an average of 180 damage, possibly exploding a CR 11+ monster.

That and I am a science teacher. What did you expect? Let it slide?

[Beardbarian]

Alchemist's fire works the same way as napalm. It doesn't explode, it burns.
The area damage is for the "splash" prorpiety

[ellindsey]

If you are willing to bring actual real-world physics into it, Alchemist's Fire seems to need oxygen to burn (since it won't burn until exposed by air). So the burn rate of a pile of burning Alchemist's fire will be limited by the inflow of oxygen. It will burn for the 50d6 damage, but not all at once - maybe more like 5d6 a round for 10 rounds or something like that.

[Magesmiley]

I'd suggest using the square root of the number of flasks to figure the number of dice. So it goes up, but not grossly. Or 7 dice of damage, for 50 flasks.

This is assuming that most of the alchemist's fire stays in one square. If it splatters out some, you're going to see a less concentrated effect.

If you're working on this assumption that some of it splatters and are trying to come up with something that is realistic, thigns get much harder. I think that I'd do something like this to figure out how much damage goes where...

Working in rings of squares like this, with ring 1 being where the alchemist's fire detonated:



6 6 6 6 6 6 6 6 6 6 6
6 5 5 5 5 5 5 5 5 5 6
6 5 4 4 4 4 4 4 4 5 6
6 5 4 3 3 3 3 3 4 5 6
6 5 4 3 2 2 2 3 4 5 6
6 5 4 3 2 1 2 3 4 5 6
6 5 4 3 2 2 2 3 4 5 6
6 5 4 3 3 3 3 3 4 5 6
6 5 4 4 4 4 4 4 4 5 6
6 5 5 5 5 5 5 5 5 5 6
6 6 6 6 6 6 6 6 6 6 6


I'd assume that half of the fire stays in the ring, and half moves to the next ring. And then repeat this process with subsequent rings.

Start with ring 1. Half the flasks go here. (25)
Out to ring 2. Half the remaining flasks go here, rounded up (13)
Out to ring 3. Half the remaining flasks go here, rounded up (6)
Out to ring 4. Half the remaining flasks go here, rounded up (3)
Out to ring 5. Half the reamining flasks go here, rounded up (2)
Out to Ring 6. Last flask goes here (1)

Then we'd need to consider the effects of the flasks being spread through the ring, so divide by the number of the square in the ring

1: 25/1
2: 13/8
3: 6/16
4: 3/24
5: 2/32
6: 1/64

And then take the square root of that...

1: 5
2. 1.27
3. .61
4. .35
5. .25
6. .125

Roughly how many dice I'd assess. Or change the fractional values into points, +1 per full .3.


So, I'd use (based on which ring the character was in):

1: 5d6
2: 1d6 + 1
3: 2 points
4: 1 point

[Red Bear]

I'd suggest using the square root of the number of flasks to figure the number of dice. So it goes up, but not grossly. Or 7 dice of damage, for 50 flasks.

This is assuming that most of the alchemist's fire stays in one square. If it splatters out some, you're going to see a less concentrated effect.

If you're working on this assumption that some of it splatters and are trying to come up with something that is realistic, thigns get much harder. I think that I'd do something like this to figure out how much damage goes where...

Working in rings of squares like this, with ring 1 being where the alchemist's fire detonated:



6 6 6 6 6 6 6 6 6 6 6
6 5 5 5 5 5 5 5 5 5 6
6 5 4 4 4 4 4 4 4 5 6
6 5 4 3 3 3 3 3 4 5 6
6 5 4 3 2 2 2 3 4 5 6
6 5 4 3 2 1 2 3 4 5 6
6 5 4 3 2 2 2 3 4 5 6
6 5 4 3 3 3 3 3 4 5 6
6 5 4 4 4 4 4 4 4 5 6
6 5 5 5 5 5 5 5 5 5 6
6 6 6 6 6 6 6 6 6 6 6


I'd assume that half of the fire stays in the ring, and half moves to the next ring. And then repeat this process with subsequent rings.

Start with ring 1. Half the flasks go here. (25)
Out to ring 2. Half the remaining flasks go here, rounded up (13)
Out to ring 3. Half the remaining flasks go here, rounded up (6)
Out to ring 4. Half the remaining flasks go here, rounded up (3)
Out to ring 5. Half the reamining flasks go here, rounded up (2)
Out to Ring 6. Last flask goes here (1)

Then we'd need to consider the effects of the flasks being spread through the ring, so divide by the number of the square in the ring

1: 25/1
2: 13/8
3: 6/16
4: 3/24
5: 2/32
6: 1/64

And then take the square root of that...

1: 5
2. 1.27
3. .61
4. .35
5. .25
6. .125

Roughly how many dice I'd assess. Or change the fractional values into points, +1 per full .3.


So, I'd use (based on which ring the character was in):

1: 5d6
2: 1d6 + 1
3: 2 points
4: 1 point

I like this, it's probably not very realistic, but it's a nice rule :smallsmile:

to everyone: Thanks for your answers and feel free to add any other comment, opinion or ideas about alchemist fire in general.

[Spore]

There's bringing physics into the process, and there's bringing math into that. Keep in mind that this is not a theoretical ballistic experiment, but a GAME and hence you really should cut down on the math here. You could basically use a bell curve to tell you the temperature (and hence the fire) of that explosion, which is quite good described with your 5d6,1d6,2,1 approach.

[Vedhin]

I believe Skip Williams had something to say on this. Specifically, that each doubling of volume increased the weapon size by one for Alchemist's Fire and other similar items.

Finding the source for me thinking this may be harder though, so this is more "a guy on the internet said another guy on the internet said that a designer unofficially ruled..."

[ddude987]

Normal splash damage X 50, so more like thermite than gas.

I'd agree there, except fire does half damage to objects. Hmm I wonder if there is a way to mobilize alchemist fire into cost effective thermite

[jindra34]

I really just needed a reason to NOT give a character the capability to deal 50d6 damage on that square equalling an average of 180 damage, possibly exploding a CR 11+ monster.

That and I am a science teacher. What did you expect? Let it slide?

Its not 50d6.
1. It would be 1d6 +/- modifers 50 times.
Except
2. Alchemist's fire only deals 1d6 on a direct hit, everything else within 5 feet takes 1 point.

So this big 'bomb' does 50 damage to anything nearby that doesn't have fire resistance. Not all that impressive now?

[ddude987]

Its not 50d6.
1. It would be 1d6 +/- modifers 50 times.
Except
2. Alchemist's fire only deals 1d6 on a direct hit, everything else within 5 feet takes 1 point.

So this big 'bomb' does 50 damage to anything nearby that doesn't have fire resistance. Not all that impressive now?

Considering it would outright garentee kill the average person, it seems impressive. Remember the standard person is level 1, maybe 2, npc class with 10 con. 50 damage puts them more than dead. Though the blast radius is a bit small, only hitting 8 other people maximum unless they were squeezing, like being in a crowd.

[Jeff the Green]

Bonus question: Is there a real world substance that catches on fire when exposed to air like Alchemist's fire does? What happens if you break 50 flask of this substance at once?

You're looking for pyrophoric substances (http://en.wikipedia.org/wiki/Pyrophoricity). tert-Butyllithium comes to mind, along with arsine gas. I've never actually worked with them, as I didn't take any chem labs past organic chemistry, but I'd expect that with adequate space and ventilation you'd get a fire twice as voluminous and roughly as hot. With inadequate space you'd get a hotter fire, and with inadequate ventilation you'd lose all the oxygen.

However, alchemist's fire isn't pyrophoric, it's hypergolic with everything other than its vial. In other words, if you were to bury the flask in wet sand and apply the right force to the sand to break the vial, the alchemist's fire would still ignite. So we're looking for something like chlorine trifluoride (http://pipeline.corante.com/archives/2008/02/26/sand_wont_save_you_this_time.php). (The entire "Things I Won't Work With" series may give you other ideas on what it might be. Also possibly ideas of why you should stay away from certain chemistry labs or ideas of how to destroy property, depending on your bent.)

[Darrin]

So this big 'bomb' does 50 damage to anything nearby that doesn't have fire resistance. Not all that impressive now?

50 damage in a 5' radius that bypasses DR and can't be avoided via a saving throw would still be pretty darned useful, even at higher levels. For comparison, a 20d6 fireball does 35 damage on average on a successful Ref save (or zero damage with Ref save + Evasion).

Make it Acidic Fire (Eberron Campaign Setting), and that's 100 damage, no save. Add the Grenadier feat and it's 200 damage.

[TuggyNE]

50 damage in a 5' radius that bypasses DR and can't be avoided via a saving throw would still be pretty darned useful, even at higher levels. For comparison, a 20d6 fireball does 35 damage on average on a successful Ref save (or zero damage with Ref save + Evasion).

Make it Acidic Fire (Eberron Campaign Setting), and that's 100 damage, no save. Add the Grenadier feat and it's 200 damage.

For reference, a balor's death throe does 100 flat damage (admittedly, in a much larger area), and it actually has a save (admittedly, a fairly high one).

[Spore]

50 damage in a 5' radius that bypasses DR and can't be avoided via a saving throw would still be pretty darned useful, even at higher levels. For comparison, a 20d6 fireball does 35 damage on average on a successful Ref save (or zero damage with Ref save + Evasion).

Make it Acidic Fire (Eberron Campaign Setting), and that's 100 damage, no save. Add the Grenadier feat and it's 200 damage.

Shouldn't you add in the Int mod of an Alchemist in PF RAW for EVERY Alchemist's fire? aka, holy bajebus, 300 fire damage (20 Int).

[jindra34]

Shouldn't you add in the Int mod of an Alchemist in PF RAW for EVERY Alchemist's fire? aka, holy bajebus, 300 fire damage (20 Int).

If the alchemist is setting them off yes.

Edit: Er... Maybe its only for splash weapons, and its the DM's call whether a bundle detonated in such a manner is still considered a splash weapon as they are by definition thrown. Also its (1+int)*50 so fire resistance and such will take a big chunk out of it.

[Red Bear]

I believe Skip Williams had something to say on this. Specifically, that each doubling of volume increased the weapon size by one for Alchemist's Fire and other similar items.

Finding the source for me thinking this may be harder though, so this is more "a guy on the internet said another guy on the internet said that a designer unofficially ruled..."

I like this rule very much, I have a problem after 32 though:
1 - 1d6
2 - 2d6
4 - 3d6
8 - 4d6
16 - 6d6
32 - 8d6
64 - ?? (10d6? 12d6?)
128 - ??

I didn't find a weapon damage by size chart that goes after 8d6. Since those 50 flask could became 64 if I use this rule, I'm really interested in finding out the next damage after 8d6.

[Darrin]

I didn't find a weapon damage by size chart that goes after 8d6. Since those 50 flask could became 64 if I use this rule, I'm really interested in finding out the next damage after 8d6.

According to Monster Manual p. 304 (Improved Natural Attack), 8d6 -> 12d6.

Some people have expanded the progression beyond that, but I'm not sure if there's a consensus on how to continue the progression.

[Red Bear]

According to Monster Manual p. 304 (Improved Natural Attack), 8d6 -> 12d6.

Some people have expanded the progression beyond that, but I'm not sure if there's a consensus on how to continue the progression.

Thank you! :smallsmile:

[Devronq]

Just a though I believe total emmeraion in lava only deals 20d6 damage so I don't think any amount of alchemist fire would ever be able to deal even that much damage even if there was thousands of them lava is hotter and more dangerous, I'd say cap it at 10d6 damage.

[ArqArturo]

Whooboy, bringing physics into D&D. [Insert catgirl killing jokes here]

One of my friends is majoring in Physics, and he's voice of reason when someone tries to bring physics into the game.

Player: B-but-the weight of my mace should've made the armor bend, and thus cause more damage.
Him: ... Man, it's magic!
Player: But--
Him: Magic! *jazz hands*

Yes, that did happen recently :smallbiggrin:.

[Vedhin]

I like this rule very much, I have a problem after 32 though:
1 - 1d6
2 - 2d6
4 - 3d6
8 - 4d6
16 - 6d6
32 - 8d6
64 - ?? (10d6? 12d6?)
128 - ??

I didn't find a weapon damage by size chart that goes after 8d6. Since those 50 flask could became 64 if I use this rule, I'm really interested in finding out the next damage after 8d6.

I belive the 3.0 Arms & Equipment Guide had the rule for this. After you hit 3d8 or 3d8, the number of dice for a given size is twice that of two sizes lower. For example, the 3d6, 6d6, 12d6 progression is interwoven with the 2d6, 4d6, 8d6, 16d6 progression.

[Captnq]

I'd be facinated to find any rule from A&EG about multiple flasks, because I've never seen it.

By the rules, it goes off. Everything within 4' gets hit with 1 point of splash damage. If the target has 1 point of fire resistance, he LAUGHS, because each point of damage is applied seperately.

What the guy wants is a:
DITHERBOMB
- RACES OF THE DRAGON (3.5)
Simple Thrown Ammunition (Calculus)
Cost: (Weak) 100 gp, (Strong) 300 gp, (Wyrm) 1,000 gp
Alchemy DC: 25
Range: 10 ft
Weight: (Weak) 1/2 lb, (Strong) 1/2 lb (Wyrm) 1 lb


You can even load it into a gnome calculus and hurl that sucker.
And since it's ammunition (If you can load it into a weapon, it's ammo.), you can enchant it like ammunition. Put fireballs and explosion, and all sorts of crap in it. But a Augment crystal on the gnome calculus. Really stack on the fun.

Or, you could go with:
EXPLOSIVE PACK
- SECRETS OF SARLONA (3.5)
Simple Thrown Ammunition (Pack)
Cost: 200 gp (2 lbs)
Alchemy DC: 26 to 35
Range: 5 ft
Weight: 2 lb/1d6

Every 2 pounds it does 1d6 damage. Max 10d6. But for the damage to weight ratio, go with a ditherbomb.

I suppose the explosive pat delivers more damage over a wider area consistantly better then a ditherbomb, but technically, it's not ammunition. So No enchanting the crap out of one.

[Vedhin]

I'd be facinated to find any rule from A&EG about multiple flasks, because I've never seen it.

The rule for flasks is from Skip Williams, chained through multiple people on the internet. Highly dubious, but I think it's right.

The A&EG, as it turns out, does not have a hard and fast rule for weapon damage size increases, but it does have nice tables, all of which follow the alternating doublings rule I mentioned. One even goes up to 24 dice.



By the rules, it goes off. Everything within 4' gets hit with 1 point of splash damage. If the target has 1 point of fire resistance, he LAUGHS, because each point of damage is applied seperately.

He then screams in pain because Resistance To Energy (http://www.d20srd.org/srd/specialAbilities.htm#resistanceToEnergy), unlike DR, is per round, not per attack.


A creature with resistance to energy has the ability (usually extraordinary) to ignore some damage of a certain type each round, but it does not have total immunity.
Each resistance ability is defined by what energy type it resists and how many points of damage are resisted. It doesn’t matter whether the damage has a mundane or magical source.
When resistance completely negates the damage from an energy attack, the attack does not disrupt a spell. This resistance does not stack with the resistance that a spell might provide.

[Artillery]

According to Monster Manual p. 304 (Improved Natural Attack), 8d6 -> 12d6.

Some people have expanded the progression beyond that, but I'm not sure if there's a consensus on how to continue the progression.

I believe the consensus was that at for every 2 size categories you increase your damage doubles, this is the long term pattern not the short term one at medium size. Treat d12s as 2d6 for scaling purposes, 2d4 are just like 1d8.

1d2>1d3>1d4>1d6>1d8>2d6>3d6>4d6>6d6>8d6>12d6>16d6
Following the same pattern it goes
24d6>32d6>48d6>etc

For a d10 base weapon its instead 1d10>2d8>3d8... then follows the same pattern but with d8s instead of d6s.

[aeauseth]

I've already come across this in my campaign. In my case they had a sack of 20 alchemists fires they set up as a trap. As the foes charged forward they used another alchemists fire to ignite the sack of alchemists fires.

Stacking damage (as some posters have suggested) can be problematic. Instead I ruled that extra alchemist's fires extend the duration and/or area of effect. Never dealing more than 1d6 damage per round. For simplicity I didn't allow the splash damage to stack either. The creatures in the area either took 1d6 fire damage OR 1 point of slash damage (regardless of how many splashes they got) in one round.

[molten_dragon]

If there are 50 flasks of Alchemist's fire in a 5 feet sided cube and a player casts shatter (or he breaks them all at once in any other way). What do you think the effect should be? How much damage should it do? How large the effect should be?

Bonus question: Is there a real world substance that catches on fire when exposed to air like Alchemist's fire does? What happens if you break 50 flask of this substance at once?

It would have the effect of 50 flasks of alchemist's fire going off all at once. That is 50d6 damage to whatever was in the square with the alchemist's fire, and 50 damage to anything within 5 feet of that square.