D&D 5E Dragon's breath weapon vs wall

[jgsugden]

If you roll the PCs into the discussion and assume that if they're caught in the area of a dragon breath they take damage like an inanimate object in the real world would in an inferno, nothing makes sense.

For me, I think of hps as toughness, not health. When you take damage, it is not a cut, burn or bruise - it is something you gutted through and avoided taking the brunt of when it was delivered, but at the expense of using up your energy. When the energy wanes, and hps are gone, that is when you truly get hurt. So when a dragon breathes down on you and you're in the center of a 90' cone, I describe it as you diving out of the cone, even if that is not what the positioning of minis describes.

 

[Oofta]

Like I said there are a lot of variables. In TOH they did in fact attack the mortar. I remember them using a hand-held pick-axe, a crowbar and something else (just can't remember what). This technique wouldn't really work for an exterior castle wall, but it could be effective for some other types of stone walls.

FYI, I have done quite a bit of concrete work and some masonry work in my time and have or had most of the tools needed to work stone by hand. The type of stone makes a big difference too.

Also, did you know it is possible for a human to run through a single-wythe brick wall and for concrete to explode from to much heat.

True enough about the type of stone. Soft sandstone or soapstone? You can hack through it with a pickaxe. I'm thinking something you'd actually want to build out of though, like a hard granite.

But again, I'm not talking about pulling out weak mortar - that, along with using sappers to take out a wall is a whole different thing.

 

[Asisreo]

Depending on the stone, it can melt under relatively cool temperatures. Dragon's breath isn't flamethrowers, they're very hot. Hot enough to cook an average person in less than 6 seconds. Unless the wall was made specifically to be insulating, I'd think a good majority would turn molten.

 

[Dausuul]

I've had to break a few inches of ice before. It is tough stuff. I can imagine if I had a block of ice 1 foot thick, and I hit it with a sledgehammer (equivalent to a maul) I probably would not split it in half. I'd take a chunk out, but not destroy it.

An inch thin sheet of stone? Broken, I would be shocked if it could stand up to more than a single hammer blow.

If you're going to bring realistic physics into it, then you have to also reckon with the thickness of a real castle wall, which is way more than six inches. The thickness of a castle wall is measured in feet, and not just one or two of them. The thinnest figure I can find is 6 feet.

So, even if we go with wall of ice hit points, it should still be far in excess of 27 hp.

 

[Oofta]

If you're going to bring realistic physics into it, then you have to also reckon with the thickness of a real castle wall, which is way more than six inches. The thickness of a castle wall is measured in feet, and not just one or two of them. The thinnest figure I can find is 6 feet.

So, even if we go with wall of ice hit points, it should still be far in excess of 27 hp.

Yep. Castle walls can be up to 30 ft thick (at least at the base). Frequently there were exterior retaining walls of solid stone and then interiors that were filled with loose rock and rubble.

 

[dave2008]

Hi there, first time poster here.

I'm planning to throw an adult red dragon to my party's fort, and was wondering how would it's fire breath interact with their stone walls. Each 10x10 section of the wall has 17 AC and 27 HP, and the dragon's breath does 63 fire damage on average. The cone doesn't reach around corners, so they have that going for them.
rule it?

Welcome - I hope we can help!

First, how thick is the wall. You say it is a "fort" so I am assuming it is not a 10' - thick castle wall. I would say the thickness of the wall would have a major impact on the damage it can take.

 

[NotAYakk]

A wall of stone has 30 HP/inch/10'x10' area.

I'd say that dragon breath deals its full damage to each 5'/5' area. So about 7 HP per inch.

Granting stone resistance to fire seems reasonable. So for every 15 damage, you destroy an inch of stone.

So 63 damage destroys a 4 inch deep layer of stone.

This is suitably awesome and yet not completely bonkers.

A mortared stone wall, I might double that, as the mortar falls apart.

 

[Chaosmancer]

If you're going to bring realistic physics into it, then you have to also reckon with the thickness of a real castle wall, which is way more than six inches. The thickness of a castle wall is measured in feet, and not just one or two of them. The thinnest figure I can find is 6 feet.

So, even if we go with wall of ice hit points, it should still be far in excess of 27 hp.

I don't disagree with that.

I had never run across the wall of stone hp before though, I was startled by it. I brought in physics just to talk about why I thought those numbers were not accurate.

 

[Nitrosaur]

First things first, thank you all for your interest. This week has been, and it's going to be very busy for me for life-related issues, but I'll try to answer some comments when I find some time. In the end, my party cheaped out and got wooden walls instead of stone walls, but there's still stone structures for the dragon to attack, so the discussion is still worth it.


On a related note, I planned the dragon to be the final boss of the campaign, but my party, for unrelated reasons to the dragon, is very heavy on fire resistance (the only one without it is the druid, who can get protection from energy), so I realized an adult red dragon may not be enough to make a climactic finale for a party of 4-5 level 15 characters, even with variant spellcasting and an stolen magic item. It's lair has a lot of lava, but still, it would be great to see your opinions.

I've been toying with these ideas: Give it minions, make it ancient (or a homebrew point in between, old or something like that, ancient white dragon level), and give it a secondary breath weapon like that of a metallic dragon that burns away fire defenses (inmunity becomes resistance, resistance becomes nothing and nothing becomes vulnerability). Thoughts?

 

[Oofta]

First things first, thank you all for your interest. This week has been, and it's going to be very busy for me for life-related issues, but I'll try to answer some comments when I find some time. In the end, my party cheaped out and got wooden walls instead of stone walls, but there's still stone structures for the dragon to attack, so the discussion is still worth it.


On a related note, I planned the dragon to be the final boss of the campaign, but my party, for unrelated reasons to the dragon, is very heavy on fire resistance (the only one without it is the druid, who can get protection from energy), so I realized an adult red dragon may not be enough to make a climactic finale for a party of 4-5 level 15 characters, even with variant spellcasting and an stolen magic item. It's lair has a lot of lava, but still, it would be great to see your opinions.

I've been toying with these ideas: Give it minions, make it ancient (or a homebrew point in between, old or something like that, ancient white dragon level), and give it a secondary breath weapon like that of a metallic dragon that burns away fire defenses (inmunity becomes resistance, resistance becomes nothing and nothing becomes vulnerability). Thoughts?

Minions are a good idea, solos are always going to be at a disadvantage. I've also added levels of sorcerer in the past.

Another thing is that there should never be a reason for the dragon to get into close combat until it's absolutely forced to do so. Fly around, wait for your breath weapon to recharge or attack the squishies using your superior reach.

If fire doesn't work then a red dragon will be at a disadvantage but is it fire resistance or immunity? Of course you could also just give them a feat similar to Elemental Adept but that might be pushing it a bit.

Other options include blinding smoke that limits visibility because the dragon can rely on blindsight and then sneak up.

Adult dragons can carry up to 1,620 pounds (27 x 15 x 4 for large) or double that if you consider them a quadruped. So fly high overhead at night and drop things on them.

But if the PCs have a chance to corner the dragon, attrition is your friend. If they can go nova on it it's likely to be a lot easier than expected.