The Heat Metal spell reads that "Any creature in physical contact with the object takes 2d8 fire damage when you cast the spell." Since "fire damage" is, technically,, burning or heating to the point of causing physical damage, could that same damage be effective on wood? The case in point I'm thinking about is that if a character casts Heat Metal on an inset metal lock on a door or a chest (not a padlock, but the kind set into the wood itself), and concentrated for the 1 minute duration of the spell, doing damage each round, would the surrounding wood smolder? Burst into flames? And would the wood be so weakened by the fire damage that a good swift kick or blow from a hammer be enough to knock the lock free of the surrounding wood?
Up to the DM, but I would certainly allow it. The application is far more limited than knock, and realistically a wooden door could have been broken down anyway, so it doesn't take away from the spell (always important to check if an unorthodox use of a spell replicates another spell's effect).
I agree with the others above, that I would generally allow it as a creative use of the spell in a specific situation.
But to be clear, in a combat setting per RAW the answer is no - nothing is damaged by this spell except a creature that is holding, wearing or touching the heated metal.
The target of the spell is a manufactured metal object (in this case the lock) and anyone in contact suffers 2d8 fire damage.
RAW doesn't cover what happens to other objects in contact with a red-hot metal object but we can all guess. Flammable objects should catch fire. Any object should take damage.
So I would allow it even if it's not in the RAW.
Jeremy Crawford said in an interview if all you do is play RAW he hopes you're having fun with whatever you're playing but it's NOT dungeons & dragons.
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Realistically, not that realism has a lot to do with D&D, if you take a pan that's hot enough to burn a human pretty severely and put it on a wooden surface, the wood is unlikely to do more than darken slightly.
Realistically, not that realism has a lot to do with D&D, if you take a pan that's hot enough to burn a human pretty severely and put it on a wooden surface, the wood is unlikely to do more than darken slightly.
2d8 fire damage is not just a mere burn wound. That is an insta-kill for every commoner.
The target of the spell is a manufactured metal object (in this case the lock) and anyone in contact suffers 2d8 fire damage.
RAW doesn't cover what happens to other objects in contact with a red-hot metal object but we can all guess. Flammable objects should catch fire. Any object should take damage.
So I would allow it even if it's not in the RAW.
Jeremy Crawford said in an interview if all you do is play RAW he hopes you're having fun with whatever you're playing but it's NOT dungeons & dragons.
But would you allow a metal part of a manufactured object, such as a door lock, be treated as a separate object for purposes of the spell?
I don't know if I'd accept it in every case, ever but in the case of Heat Metal defeating a mundane wooden door it's not a problem.
Heat Metal is a 2nd level spell and requires concentration doing 2d8 fire damage per round for up to a minute.
A wooden door with a metal lock is a medium to large (or larger) object, based on stats for generic objects that would put it at 4d8 to 5d10 hp giving roughly 2-5 rounds to burn the door until it is "broken" or fewer if I decide its vulnerable to fire damage.
A couple other 2nd level spells that could apply to this scenario:
Knock straight up unlocks doors and is not concentration but is quite noisy. Enlarge/Reduce could theoretically shrink the door off it's hinges which I'd also consider to be a pretty noisy event, cracking and creaking wood and bending nails and all that.
If I want to balance this in terms of those other spells and detectability a door set on fire would not only give off light but also likely fill a poorly ventilated corridor with with smoke, able to be seen and smelled. Doing this outdoors could be even more visible with a very clear smoke trail leading up into the heavens.
Realistically, not that realism has a lot to do with D&D, if you take a pan that's hot enough to burn a human pretty severely and put it on a wooden surface, the wood is unlikely to do more than darken slightly.
2d8 fire damage is not just a mere burn wound. That is an insta-kill for every commoner.
Put someone in a 300F suit of plate mail and they're gonna die. There's some issue of scale, large objects with a lot of contact area don't need to be nearly as hot as smaller objects.
Just rechecked the spell. It explicitly states, that the target object glows red hot. For iron and steel that is around 900°F / 460°C. That is more than enough to ignite paper and cloth, and wood should burn with enough oxygen.
The Heat Metal spell reads that "Any creature in physical contact with the object takes 2d8 fire damage when you cast the spell." Since "fire damage" is, technically,, burning or heating to the point of causing physical damage, could that same damage be effective on wood? The case in point I'm thinking about is that if a character casts Heat Metal on an inset metal lock on a door or a chest (not a padlock, but the kind set into the wood itself), and concentrated for the 1 minute duration of the spell, doing damage each round, would the surrounding wood smolder? Burst into flames? And would the wood be so weakened by the fire damage that a good swift kick or blow from a hammer be enough to knock the lock free of the surrounding wood?
Unless your DM is deliberately being obtuse, the wood will take the fire damage, but the DMG hasn't got very good guidelines for how fire damage will impact the door. Here's what I can tell you for certain:
Door: 18 hit points, AC 15
Lock: 2 hit points, AC 19 (after this damage you've ruined the lock, I'm not saying 2 hp of damage melts the entire thing); 5 hit points if you treat it as a resilient object, so 5 hit points before it's just a lump of metal in the door.
Here's what I can guess at:
Based on the rules for murdering ships found in the DMG and Ghosts of Saltmarsh, wood seems to have no particular resistance to fire damage. I would assume as a corollary that the metal lock does have resistance, to represent that it needs to be much hotter than the wood in order to melt.
Based on the DMG's guidance, I would assume neither the lock nor the door has a damage threshold, as this is described as only being for particularly large objects.
What I can't guess at:
Should either object have any damage reduction (like the heavy armor master feat grants)? The DMG doesn't discuss it. We'll assume no, I just want to be explicit about this assumption.
So if you cast the spell and roll average numbers (i.e. 9 damage every round), it'll be something like this on each round:
You slag the lock - it glows bright red - and the door starts to visibly burn as you take it to half health. No one can lock or unlock the lock now - the mechanism inside has gone soft and lost its shape.
The metal cylinder holding the lock slags - it's now just a cylinder. Sticking anything into it is a non-starter, as is trying to see through it - it's just a lump of metal now. The wood around the lock is now so thoroughly burned (you've reduced the door to 0 hit points) that a kick from anyone would free the door from the lock as the wood would give way; unless someone touches it, you have a door-sized fire in front of you.
You've now taken the door into the negatives, if it had such a thing. It's basically made of charcoal at this point, burning still, but fragile - that kick from above would make the whole door collapse to the ground in a pile of ash. The cylinder that held the lock has gone runny. Around this point I tell you as your DM that the spell ends because the object you were targeting has ceased to be (I never let people target volumes of liquid as 1 object, or the rules break down), but the door is also an ex-door at this point, so you don't need to worry I'm being a jerk.
The door just collapses to the ground in a pile of ash and soot on its own, still smoldering. There's a saggy metal lump hissing slightly to one side.
And there you have it. 2d8 damage per round is no joke against an object with 18 hit points.
As others have mentioned here, obviously this violates the RAW - heat metal claims it deals fire damage only to creatures touching the metal, meaning the metal doesn't actually heat, and neither the metal object nor any object touching it takes any fire damage. But that's stupid, and I would houserule that heat metal heats metal.
This situation is not that big a thing but the precedent.... It is a niche spell but when it is useful it is usually really powerful. It does not need any extra power.
Which is precisely why I said "I don't know if I'd accept it in every case, ever." Precedents are for courtrooms and practicing law. The DM is there to adjudicate things on the fly on a situation by situation basis.
This situation is not that big a thing but the precedent.... It is a niche spell but when it is useful it is usually really powerful. It does not need any extra power.
Which is precisely why I said "I don't know if I'd accept it in every case, ever." Precedents are for courtrooms and practicing law. The DM is there to adjudicate things on the fly on a situation by situation basis.
Consistency is very important for DM's. If something works in one situation, players will expect similar to work in other situations. And if they don't they will enjoy the campaign a lot less.
Be consistent sure, but recognize that even the DM isn't going to rule perfectly in every scenario.
A DM can be consistently hold the stance: "It seems reasonable in this situation, sure, I'll allow it but I reserve the right to veto it if it becomes a problem in the future." That's all that I mean by not being beholden to a precedent.
Thanks, gang! I'm loving the input and perspectives in response to my original question. Having been DM'ing since 1978, I have always regarded the rules as guidelines for enjoyable play, so RAW rarely hold forth in my games, but they are great guardrails from things spinning out of control.
There are so many variables in the game that it does fall on the DM to be as consistent as possible (although there are magic effects and dimensions that even make consistency a somewhat waffly concept at times.)
I've often thought that merely labeling damage without some visual/residual/viable effect is sloppy. Force damage, for instance. How does that manifest in game? I often have it rock the recipient to some extent, even calling for Dexterity-related ability scores to keep from being knocked over if the numbers are sufficient. And I often describe the effect as massive bruising.
Fire damage, to me, is somewhat more obvious and easier to dictate in terms of the effects. To those who have responded to my original question with the RAW tack of it only affecting a creature in contact with the metal, consider the outcome of a treant - a creature made of wood (per the MM) - armed with a great sword. The limb grasping the weapon would sustain the fire damage and why is that wood any different than the wood of a door? Because it is part of a sentient creature? Interesting argument, perhaps.
"Damage" is already such an arbitrary rule-system concept, don't chase logical implications to objects too far down the rabbit hole. A person takes 2d8 fire damage, and has a discrete pool of hit points before they fall unconscious. For objects however... this system is... different.
Hit Points
An object's hit points measure how much damage it can take before losing its structural integrity. Resilient objects have more hit points than fragile ones. Large objects also tend to have more hit points than small ones, unless breaking a small part of the object is just as effective as breaking the whole thing. The Object Hit Points table provides suggested hit points for fragile and resilient objects that are Large or smaller.
Size
Fragile
Resilient
Tiny (bottle, lock)
2 (1d4)
5 (2d4)
Small (chest, lute)
3 (1d6)
10 (3d6)
Medium (barrel, chandelier)
4 (1d8)
18 (4d8)
Large (Cart, 10-ft.-by-10-ft. window)
5 (1d10)
27 (5d10)
Damage Threshold
Big objects such as castle walls often have extra resilience represented by a damage threshold. An object with a damage threshold has immunity to all damage unless it takes an amount of damage from a single attack or effect equal to or greater than its damage threshold, in which case it takes damage as normal. Any damage that fails to meet or exceed the object's damage threshold is considered superficial and doesn't reduce the object's hit points.
A door will "lose its structural integrity" when it takes a certain amount of fire damage, but will fire damage cause it to char? How much damage? Does it have a damage threshold, such that only fire damage over a certain amount (5? 10?) causes it damage? Does charring have a temperature threshold, or a damage threshold? Is it the fire damage that's doing the charring, or just the narrative consequence of wood touching hot metal?
RAW, Heat Metal says nothing about charring wood in contact with the metal. Logically, very hot metal can char wood, but doesn't always, or doesn't always immediately. Beyond that, the DM just needs to make a ruling based on what's useful to tell the story; as a player, I certainly wouldn't expect that I'd be in a position to make any assumptions either way.
The Heat Metal spell reads that "Any creature in physical contact with the object takes 2d8 fire damage when you cast the spell." Since "fire damage" is, technically,, burning or heating to the point of causing physical damage, could that same damage be effective on wood? The case in point I'm thinking about is that if a character casts Heat Metal on an inset metal lock on a door or a chest (not a padlock, but the kind set into the wood itself), and concentrated for the 1 minute duration of the spell, doing damage each round, would the surrounding wood smolder? Burst into flames? And would the wood be so weakened by the fire damage that a good swift kick or blow from a hammer be enough to knock the lock free of the surrounding wood?
Up to the DM, but I would certainly allow it. The application is far more limited than knock, and realistically a wooden door could have been broken down anyway, so it doesn't take away from the spell (always important to check if an unorthodox use of a spell replicates another spell's effect).
The metal lock itself would be a discrete object, set within the wood of the door. That seems (to me) to be a viable target for the spell.
I agree with the others above, that I would generally allow it as a creative use of the spell in a specific situation.
But to be clear, in a combat setting per RAW the answer is no - nothing is damaged by this spell except a creature that is holding, wearing or touching the heated metal.
The target of the spell is a manufactured metal object (in this case the lock) and anyone in contact suffers 2d8 fire damage.
RAW doesn't cover what happens to other objects in contact with a red-hot metal object but we can all guess. Flammable objects should catch fire. Any object should take damage.
So I would allow it even if it's not in the RAW.
Jeremy Crawford said in an interview if all you do is play RAW he hopes you're having fun with whatever you're playing but it's NOT dungeons & dragons.
Realistically, not that realism has a lot to do with D&D, if you take a pan that's hot enough to burn a human pretty severely and put it on a wooden surface, the wood is unlikely to do more than darken slightly.
2d8 fire damage is not just a mere burn wound. That is an insta-kill for every commoner.
I don't know if I'd accept it in every case, ever but in the case of Heat Metal defeating a mundane wooden door it's not a problem.
Heat Metal is a 2nd level spell and requires concentration doing 2d8 fire damage per round for up to a minute.
A wooden door with a metal lock is a medium to large (or larger) object, based on stats for generic objects that would put it at 4d8 to 5d10 hp giving roughly 2-5 rounds to burn the door until it is "broken" or fewer if I decide its vulnerable to fire damage.
A couple other 2nd level spells that could apply to this scenario:
Knock straight up unlocks doors and is not concentration but is quite noisy.
Enlarge/Reduce could theoretically shrink the door off it's hinges which I'd also consider to be a pretty noisy event, cracking and creaking wood and bending nails and all that.
If I want to balance this in terms of those other spells and detectability a door set on fire would not only give off light but also likely fill a poorly ventilated corridor with with smoke, able to be seen and smelled. Doing this outdoors could be even more visible with a very clear smoke trail leading up into the heavens.
Put someone in a 300F suit of plate mail and they're gonna die. There's some issue of scale, large objects with a lot of contact area don't need to be nearly as hot as smaller objects.
Just rechecked the spell. It explicitly states, that the target object glows red hot. For iron and steel that is around 900°F / 460°C. That is more than enough to ignite paper and cloth, and wood should burn with enough oxygen.
Unless your DM is deliberately being obtuse, the wood will take the fire damage, but the DMG hasn't got very good guidelines for how fire damage will impact the door. Here's what I can tell you for certain:
Door: 18 hit points, AC 15
Lock: 2 hit points, AC 19 (after this damage you've ruined the lock, I'm not saying 2 hp of damage melts the entire thing); 5 hit points if you treat it as a resilient object, so 5 hit points before it's just a lump of metal in the door.
Here's what I can guess at:
Based on the rules for murdering ships found in the DMG and Ghosts of Saltmarsh, wood seems to have no particular resistance to fire damage. I would assume as a corollary that the metal lock does have resistance, to represent that it needs to be much hotter than the wood in order to melt.
Based on the DMG's guidance, I would assume neither the lock nor the door has a damage threshold, as this is described as only being for particularly large objects.
What I can't guess at:
Should either object have any damage reduction (like the heavy armor master feat grants)? The DMG doesn't discuss it. We'll assume no, I just want to be explicit about this assumption.
So if you cast the spell and roll average numbers (i.e. 9 damage every round), it'll be something like this on each round:
And there you have it. 2d8 damage per round is no joke against an object with 18 hit points.
As others have mentioned here, obviously this violates the RAW - heat metal claims it deals fire damage only to creatures touching the metal, meaning the metal doesn't actually heat, and neither the metal object nor any object touching it takes any fire damage. But that's stupid, and I would houserule that heat metal heats metal.
Which is precisely why I said "I don't know if I'd accept it in every case, ever." Precedents are for courtrooms and practicing law. The DM is there to adjudicate things on the fly on a situation by situation basis.
Be consistent sure, but recognize that even the DM isn't going to rule perfectly in every scenario.
A DM can be consistently hold the stance: "It seems reasonable in this situation, sure, I'll allow it but I reserve the right to veto it if it becomes a problem in the future." That's all that I mean by not being beholden to a precedent.
Thanks, gang! I'm loving the input and perspectives in response to my original question. Having been DM'ing since 1978, I have always regarded the rules as guidelines for enjoyable play, so RAW rarely hold forth in my games, but they are great guardrails from things spinning out of control.
There are so many variables in the game that it does fall on the DM to be as consistent as possible (although there are magic effects and dimensions that even make consistency a somewhat waffly concept at times.)
I've often thought that merely labeling damage without some visual/residual/viable effect is sloppy. Force damage, for instance. How does that manifest in game? I often have it rock the recipient to some extent, even calling for Dexterity-related ability scores to keep from being knocked over if the numbers are sufficient. And I often describe the effect as massive bruising.
Fire damage, to me, is somewhat more obvious and easier to dictate in terms of the effects. To those who have responded to my original question with the RAW tack of it only affecting a creature in contact with the metal, consider the outcome of a treant - a creature made of wood (per the MM) - armed with a great sword. The limb grasping the weapon would sustain the fire damage and why is that wood any different than the wood of a door? Because it is part of a sentient creature? Interesting argument, perhaps.
"Damage" is already such an arbitrary rule-system concept, don't chase logical implications to objects too far down the rabbit hole. A person takes 2d8 fire damage, and has a discrete pool of hit points before they fall unconscious. For objects however... this system is... different.
A door will "lose its structural integrity" when it takes a certain amount of fire damage, but will fire damage cause it to char? How much damage? Does it have a damage threshold, such that only fire damage over a certain amount (5? 10?) causes it damage? Does charring have a temperature threshold, or a damage threshold? Is it the fire damage that's doing the charring, or just the narrative consequence of wood touching hot metal?
RAW, Heat Metal says nothing about charring wood in contact with the metal. Logically, very hot metal can char wood, but doesn't always, or doesn't always immediately. Beyond that, the DM just needs to make a ruling based on what's useful to tell the story; as a player, I certainly wouldn't expect that I'd be in a position to make any assumptions either way.
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