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I was reading various questions about whether or not grease is flammable, which got me thinking about other flammable materials, so I'm asking what qualifies a material as flammable or not and how spells that can ignite flammable objects interact like burning hands.

For example if your party is in a forest during the summer and your fighting goblins what happens when you cast burning hands, do you start a forest fire which is likely what would happen in reality if you created a 15ft gout of flames in a dry forest.

Another example would be if your party is fighting cultists who all wear robes do the robes catch fire when hit with burning hands or other spells capable of igniting things, and if the robes do catch fire they begin taking burning damage until the robes are destroyed or extinguished.

One final example I have is what would happen if you casted burning hands on a cask of liquor that would likely be flammable which is normal for liquors that are above 100 proof(50% alcohol content), or if you casted burning hands in a alchemists lab where their would likely be many different flammable liquids.

I'm mostly wondering this to find some new and fun ways to defeat enemies early on such as somehow dousing a group of orcs in a strong liquor and lighting them up with a simple burning hands spell.

Iankill
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2 Answers2

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All editions of D&D (and indeed, almost all RPGs) are written with us and our knowledge of the world as the baseline, only adding to and altering that where it needs to and says so.

So when the game says "flammable objects", it's relying on the words "flammable" and "objects" to have their dictionary meanings, and the set of flammable objects is the same as in the real world except where the game specifically adds or removes objects from that set. Thus, a summer forest may* contain dry tinder that may* catch on fire, and normal cotton robes† may catch on fire. A cask of high-proof liquor is potentially flammable, just like in real life, but also just like in real life, it's not going to be lit by a momentary gout of flame because solid wood staves don't light instantly — to blow up a volatile liquid in a wooden cask, you have to expose it to intense heat for more than a few seconds.

* I say "may" twice, because unless you previously establish that the target is standing in dry tinder, it's only possible that the burning hands fan also hits something that could catch on fire; and because even if some tinder catches on fire, you're not guaranteed that the whole forest goes up in flames. This is where your discretion as a DM comes in: decide what a sensible chance is, and ask the dice.

† Speaking of things altered by the game rules though: if a flammable object is worn or carried by someone, it does not automatically catch on fire just because burning hands says flammable objects catch fire. Worn and carried objects always grant a saving throw against that kind of outcome.

SevenSidedDie
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  • This covers basically what I was looking for, I was going to ask about dust explosins from common things like sawdust, dust in mines, and grain, but it was too broad of a question. – Iankill Sep 24 '14 at 18:03
  • O, you knew it was coming. Object, at least, has a D&D 3.5 definition. "Anything with no Charisma score is an object, not a creature." – Hey I Can Chan Sep 24 '14 at 19:05
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    @HeyICanChan Yes, but that's a "qualification definition". It's a modifier on the dictionary definition, describing what qualifies as an object; the game still expects you to know what it means when it says something "is an object". (There are other rules about objects, I know, but they are still not an exhaustive replacement for the dictionary meaning, just piecemeal modifications.) – SevenSidedDie Sep 24 '14 at 19:07
  • +1 here, but do note that most fire damage spells create short bursts of fire that don't significantly raise the temperature of the area of effect, other than sensitive fleshy targets. That's why spells like fireball specify that only easily flammable items like paper catch fire - the spell is designed for to be able to be used without burning down structures or endangering the caster. A few spells, though, specifically say they catch much more on fire, I believe scorching ray is one of them, they cause much more "fun". – gatherer818 Sep 24 '14 at 20:36
  • @gatherer818 The fireball spell says, "The fireball sets fire to combustibles and damages objects in the area. It can melt metals with low melting points, such as lead, gold, copper, silver, and bronze" and can continue on past barriers it breaks (PH 231). The fireball spells in 1E and 2E did the same except overpressured instead of breaking barriers. In all fairness, my 2E DM adjudicated fireball the way you describe, and I don't know why. – Hey I Can Chan Sep 25 '14 at 07:42
  • @HeyICanChan ooh, I'd forgotten the melting metals point. I like that. I wonder which spell I'm thinking of - or which edition, as they all run together in my head. Still, instantaneous fire spells don't typically set MUCH on fire. Duration fire spells are much, much more fun for pyromaniacs. – gatherer818 Sep 25 '14 at 09:07
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If it would burn in real life, then it burns in the gameworld. The forest is flammable; the cultists' robes are flammable; the casks and alchemical liquids are all likely to be flammable. And, of course, many things the PC is carrying are flammable too.

However. 3e introduced a saving throw for burning hands, so if the cultists make theirs the normal ruling is that their items are safe. 1e had item saving throws, so if your system has those then perhaps the trees and the casks etc. will have make a save too.

But, yes, careful use of burning hands can cause havok among your enemies while careless use can cause them equal levels of amusement.

Gregory Avery-Weir
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Nagora
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  • 3e still has saving throws for items, they just rarely come into play for worn/wielded items, preferring to use the saving throw of whoever is wearing/wielding them. So you usually only see it get used with unattended items. – KRyan Sep 24 '14 at 19:01