Casting a fireball in a crypt/cave/mine: Possible consequences?

[MonkeySage]

Last game I ran, the players entered a crypt to purge a ghoul nest within. The wizard thought it might be a good idea to cast a fireball, so i checked to see if structural integrity could be maintained, then had my players roll fort saves. I based the DC on proximity to the blast epicenter, and the one player that failed, I told them they were suffocating.

At the time, I was only trying to think of a creative way to have a silly move backfire, since it would normally be a bad idea to through a highly explosive object into a closed area like that.

However, I was hoping to get a better perspective: what actually might be the consequences of casting an explosive spell like fireball into a cave/crypt/mine?

[Sebastrd]

Do your players care about that level of detail?

In my experience, nothing pisses off players more than a DM using "clever" logic and realistic physics to stop them from doing cool things.

[Jeraa]

Last game I ran, the players entered a crypt to purge a ghoul nest within. The wizard thought it might be a good idea to cast a fireball, so i checked to see if structural integrity could be maintained, then had my players roll fort saves. I based the DC on proximity to the blast epicenter, and the one player that failed, I told them they were suffocating.

At the time, I was only trying to think of a creative way to have a silly move backfire, since it would normally be a bad idea to through a highly explosive object into a closed area like that.

However, I was hoping to get a better perspective: what actually might be the consequences of casting an explosive spell like fireball into a cave/crypt/mine?

A fireball spell is not really explosive despite its description - there is no pressure. It can also burn fine underwater, so it shouldn't consume any of the oxygen in the air to cause suffocation.

[LibraryOgre]

For me, the main consequence would be that the walls should be making saving throws v. magical fire. Since Rock (which I assume the crypt was made out of) saves on a 3 or better, you're unlikely to have a collapse or anything.

If a DM pulled the "you're suffocating" bit on me, I'd probably roll with it, but ask, after the game, if that was a local rule ("The crypt had been sealed for a long time and the air was stale as it was") or if it was going to be an effect I could count on (because it can be fun to use physics to suffocate your enemies).

[Icewraith]

A fireball spell is not really explosive despite its description - there is no pressure. It can also burn fine underwater, so it shouldn't consume any of the oxygen in the air to cause suffocation.

The spell specifically states it ignites flammable objects in at least a couple editions I am familiar with. If you're going to be carrying anything resulting in an open flame into a mine (torches, continual flame, kender...), it's best to have a safety lantern or canary or something to warn you if you're in the presence of a toxic gas. Safety lantern is better because the color of the flame will change and the room won't ignite before you can react.

Also, if I'm a dwarf or other race used to being underground, I'm keeping an eye out for coal seams, especially if I've got fireball prepared.

[LibraryOgre]

Also, if I'm a dwarf or other race used to being underground, I'm keeping an eye out for coal seams, especially if I've got fireball prepared.

Reminds me of the time the party set off a Fuel Air Bomb in Waterdeep. On accident.

[Sliver]

Instantaneous fire comes and goes in a flash, which is why it doesn't catch creatures on fire. So I'd say that it doesn't burn off oxygen...

Mark Hall is mistaken on the saves issue, though (at least in 3.5).

Nonmagical, unattended items never make saving throws. They are considered to have failed their saving throws, so they always are affected by spells. An item attended by a character (being grasped, touched, or worn) makes saving throws as the character (that is, using the character’s saving throw bonus).

Of course, considering that fire deals half damage to objects before calculating hardness, it's really hard to do actual structural damage. Stone walls will have 8 hardness, so that's at least 18 damage you need to roll to do a single point of damage, and they usually have 60+ hp.

The risk of destroying anything with an AoE spell is so small that it's pointless to even account for, unless you are trying to surprise your players with PHYSICS.

If you never said that you are going to adjust spells and effects to have a "realistic" edge, then they would have a right to be upset with you. I advice against it, as it would only cause lengthy debates and would unbalance spells even further. Not something you want to have when trying to run your game smoothly...

[Dysart]

Well there's the obvious one of if the fireball doesn't fit then it fills gaps until it's used it's total 20ft diametre.

Other than that it's hard to punish specifically fireball as others have said it's not really a traditional explosive.

I personally would play it that it wouldn't work underwater as it's a sulfuric pellet that explodes fire... which needs oxygen to burn in my book. Which if you have that ruling on the spell then it's fine to cause it to briefly (1 turn) cause an oxygen void area.

As for specifically in a closed underground area, if it's been sealed for a while with no plant life then it may be that there is less oxygen content in there so you could rule that it has a lower maximum damage but I'd express this to the characters before you decide to make this a rule.
Especially if we're talking about a wizard with high intelligence.

Maybe in the future give them a free Knowledge Arcana roll and tell them what affect they think it might have.

[Yora]

It all depends on the game system. Which hasn't been mentioned so far at all.

[Icewraith]

Well there's the obvious one of if the fireball doesn't fit then it fills gaps until it's used it's total 20ft diametre.

Other than that it's hard to punish specifically fireball as others have said it's not really a traditional explosive.

I personally would play it that it wouldn't work underwater as it's a sulfuric pellet that explodes fire... which needs oxygen to burn in my book. Which if you have that ruling on the spell then it's fine to cause it to briefly (1 turn) cause an oxygen void area.

As for specifically in a closed underground area, if it's been sealed for a while with no plant life then it may be that there is less oxygen content in there so you could rule that it has a lower maximum damage but I'd express this to the characters before you decide to make this a rule.
Especially if we're talking about a wizard with high intelligence.

Maybe in the future give them a free Knowledge Arcana roll and tell them what affect they think it might have.

20 foot radius. 40 foot diameter.

In 5e at least IIRC you have advantages on saves against fire spells if you're underwater. I don't know if anyone thought to grant disadvantage on saves against lightning spells under the same conditions.

[Beta Centauri]

There's nothing inherently silly about what the wizard wanted to do, and thus no reason to have it backfire.

If you're ever worried about what the effect of a choice could realistically be, ask the players. Whatever they tell you is what they would find realistic. Save some time and trouble and go with that. If they don't know, handwave something easy. If it's a major negative consequence for the players, that will probably give them some ideas for how the proposal should work. Go with those ideas.

[MonkeySage]

My players, including the player whose character suffocated(I stunned him for one round), seemed at least to appreciate the effect. I reasoned along the same line that one of our respondants here did, that as it consumes a sulfuric component, it does consume the oxygen in the air, magical fire or not. Though my decision was made on the spot, my players were aware of the risk involved(previously they collapsed the wooden ceiling of a cellar through the use of a fireball, which that time worked in their favor). I will take note of the statement that the fireball is just ignition and not explosion though, it makes a lot of sense.
As someone who loves to play wizards, I fully understand that given the right conditions, a wizard of 5th level or higher can steal the fight. But they have to be careful, because they or the people around them can get hurt if they make the wrong decisions.

[LibraryOgre]

Instantaneous fire comes and goes in a flash, which is why it doesn't catch creatures on fire. So I'd say that it doesn't burn off oxygen...

Mark Hall is mistaken on the saves issue, though (at least in 3.5).

The key in my statement was "save vs. magical fire", and the mechanics mentioned; I tend to take an AD&D approach to things in General.

[MonkeySage]

I recall a quote from Buffy, Willow explaining that magic "works off physics". I like that, provides a lot of opportunities to throw a bone to those who know a thing or two. so my players could use a fireball to suffocate enemies in a closed area. it didn't work like that this time because the enemies didn't need to breathe.
I love when stories try to frame their fantastical elements in things we understand. there was a surprising amount of real chemistry in fullmetal alchemist, which as a chemistry major, this made me enjoy the show even more.

[Beta Centauri]

I recall a quote from Buffy, Willow explaining that magic "works off physics". I like that, provides a lot of opportunities to throw a bone to those who know a thing or two. so my players could use a fireball to suffocate enemies in a closed area. it didn't work like that this time because the enemies didn't need to breathe.
I love when stories try to frame their fantastical elements in things we understand. there was a surprising amount of real chemistry in fullmetal alchemist, which as a chemistry major, this made me enjoy the show even more.

That's very easy to miss on, though. Real science doesn't really lend itself to anything cooler than the real world, and attempts to make it cool can be cringe inducing. Don't misuse the concept of quantum entanglement to explain your crucial plot element - I get why it's crucial, so I'll take any explanation you give me, including none. Why risk getting the real science wrong?

This, incidentally, is why the Enterprise shoots "phasers" instead of "lasers." They didn't want actual scientists writing in and telling them that lasers can't do the thing they did on the show.

If the players enjoy negative consequences as a result of "real" science working against them, great. Just be careful not to impose those consequences just because they're real.

[jedipotter]

However, I was hoping to get a better perspective: what actually might be the consequences of casting an explosive spell like fireball into a cave/crypt/mine?

Well, you might not want to go there.

A game like D&D works best with ''the spell went off just like it says in the rules on page 42'' and you move on. Adding things changes the game.

First, it's odd to ''tack stuff on''. So you want to say ''fireball sucks up all the air in an area''. Ok, that is fine. But then all the spellcasters would know that too. You would add the effect to the fireball spell description. You can't have Wizard Bob discover the effect as if he was the first person to cast fireball ever in the history of the world.

Second, if it was known about the side effect....the spell would be changed. Fireball is written as ''fire and forget'' with not much else effect. If ''version 1'' did cause air to be sucked up'', then they would just make ''version 2'' that did not suck up air. Or people would use another attack spell.

Third, ''real world'' physics are.....no fun. One one side, a fireball might have almost no effect. Or worse no game effect. Depending on the fire source, wind, temperature and lots of other things....all sorts of weird things can happen that due no harm. You can find endless stories of this happening. And on the other side, a fireball can have way too much of an effect. A single match flame and a person explodes, depending on lots of things. And you get all the ''real world'' stuff ''the fire did not burn them exactly...but the heat burned their lungs so they could not breathe.

[The Grue]

Well, you might not want to go there.

A game like D&D works best with ''the spell went off just like it says in the rules on page 42'' and you move on. Adding things changes the game.

Who are you and what have you done with jedipotter?

[Mr.Moron]

I'd probably dynamically change the shape of the blast. That is if we're talking super-confined here the spell is going to flare out from the center with longer "lines" shooting off from the point of origin rather than confined area being lost to the shape of the map.

If this extended blast would catch friendlies I'd probably ask for an intelligence or wisdom check before the player casts the spell to represent the character realizing this. Probably low. If they pass this, then I'll warn them ahead of time and give them a free take-back on the action.

Even if the fail that kind of prompt is usually enough to get the player to realize what's up, in which case they can feel free to do a take back.. if they want.

If the newly shaped blast would only catch enemies, no need for rolls or handing out information it's a nice chance for the players/PCs to learn by seeing. They'll know for next time at the poor goblin's expense.

Enemies (but probably not friendlies) close to the blast might be blown outwards and maybe slam into walls. This is more likely the worse the fight is currently going for the PCs. Much more likely if possible trajectories would give a large variety of results (such into a wall, into a pit, and into a PC with even chances).

If it's in particularly poor structural condition there might be a cave-in. It might happen on a roll or just arbitrarily happen depending on the mood at the table. If things have been going rather smoothly and predictably so far the cave in might just happen. If we've had a long string of wild and cool rolls, I'd probably announce that I'm rolling for a cave in, the mechanics behind it and then roll the die in the open.

The chance of this is usually much higher if a player mentions it. Like I probably wouldn't do the suffocation on my own, as it feels a bit heavy handed. However if player goes "Oh wait. Could that use up all the air in here?" I might go "A little bit. The problem is more the concussion knocking the wind out of you. If you spend a bonus action to brace yourselves you can get advantage on the save.". When a player asks something like that, they're hinting at their vision of the game world so it's fine to change my plan to add the complication they're expecting.

[gom jabbarwocky]

Well, one of the things about Fireball is that, if you're playing in an edition where it forms a 20' radius sphere, then, if my math is right, that amounts to a total of over 33,510 cubic feet of blazing death. That covers a lot of dungeon, so I wouldn't worry about it causing the PCs to suffocate (it's magical fire and doesn't require oxygen), but blowback causing the wizard to accidentally turn the party into barbecue. If you shoot a fireball into a chamber with a ceiling lower than 40', all that cubic footage will get pushed outwards, possibly consuming the caster if they overestimated the size of the room they were lighting up.

[LibraryOgre]

I'd probably dynamically change the shape of the blast. That is if we're talking super-confined here the spell is going to flare out from the center with longer "lines" shooting off from the point of origin rather than confined area being lost to the shape of the map.

Ahhh, the AD&D fireball and its wonderful "area of effect as determined by volume, not radius."

[Mr.Moron]

Well, one of the things about Fireball is that, if you're playing in an edition where it forms a 20' radius sphere, then, if my math is right, that amounts to a total of over 33,510 cubic feet of blazing death. That covers a lot of dungeon, so I wouldn't worry about it causing the PCs to suffocate (it's magical fire and doesn't require oxygen), but blowback causing the wizard to accidentally turn the party into barbecue. If you shoot a fireball into a chamber with a ceiling lower than 40', all that cubic footage will get pushed outwards, possibly consuming the caster if they overestimated the size of the room they were lighting up.

Well it doesn't have to be a 1-to-1 ratio. I'd only push so far as the interface seems to readily suggest more or less. If we're playing on a map with squares our interface is largely a 2d plane. Chances nobody is going to bat an eye if I think roughly in terms of squares while ignoring the ceiling and putting in a fudge factor in.

If we're playing off map it's even easier as it's just kind of vaguely confined and can just be blown out to whatever proportions feel credible in the moment.

[xroads]

This reminds me of a story I heard from a friend where a lightning bolt & fireball spell combo resulted in an unintended follow-up explosion that forced all parties in the encounter to fry.

If I remember the story correctly, a player decided to strike a submerged beastie with a lightning bolt. The next player then followed up with a fireball. Well my friend, the GM at the time, declared that the lightning bolt had seperated the oxygen from the hydrogen atoms via electrolysis. So the following fireball had the unintended consequence of igniting the oxygen.

I probably would have argued against this myself had I been there. But then again, it is an amusing story his players and himself still talk about years later.

[Jay R]

The most obvious consequence is to potential treasure. Scrolls, books, paintings, clothing, staves, wands, etc. are simply gone.

[Kami2awa]

Mine gas has come up in some older published D&D stuff, but I'd find it a bit annoying - it's not something D&D parties generally plan for, suggesting it doesn't happen very often at all in D&D worlds (otherwise anyone adventuring underground often would be aware of it). Certainly I'd give the players a hint that it's on the way, otherwise it might as well be "Rocks Fall, Everyone Dies."

Eek... imagine a mine gas elemental...

Fireball should certainly be bad for places full of flammable stuff - for Gods' sake don't use it in a library. Some editions, however, make it clear that it *doesn't* ignite other fires, which seems a little odd.

Making fireballs expand to fill the available space would be fine but I think I'd let the mage know beforehand, rather than have him find out after casting the spell! A wizard would hopefully be aware enough of how their spells work and intelligent enough not to blow himself apart, even if the player doesn't take that into account.

There's some interesting notes in the old 2e DMG about what spells do underwater. Fire-based spells generally don't work at all, Wall of Ice creates an instant ice-floe - and lightning bolt spreads out into the surrounding water so behaves like Fireball.

[goto124]

We had a thread for underwater fireballs. Some go Harry Potter and just refluff it into hot steaming water that works the same mechanically. Case by case basis.

[LooseCannoneer]

I think you would roll for damage to the walls, roof, pillars, anything in range, and cause cave-ins according to what structural support was destroyed.

[Kami2awa]

I think you would roll for damage to the walls, roof, pillars, anything in range, and cause cave-ins according to what structural support was destroyed.

Seems like that would make fireball extremely dangerous to use underground, which is unlikely as its a popular spell for dungeoneering wizards. Most dungeons would seem constructed to be fairly fireball-resistant.

Maybe if the roof is held up by rather rickety wooden props, as in a half-finished tunnel?

[goto124]

Most dungeons would seem constructed to be fairly fireball-resistant.

Nah, many wizards before have thrown fireballs and missed, thus the walls who took the damage gain XP from such spells. This extends to other misses such as a figher accidentally swinging his sword into the wall. The walls are over level 20, and very much able to take fireballs now.

[LooseCannoneer]

Nah, many wizards before have thrown fireballs and missed, thus the walls who took the damage gain XP from such spells. This extends to other misses such as a figher accidentally swinging his sword into the wall. The walls are over level 20, and very much able to take fireballs now.

The walls gain xp from all kills in that room.

[LokiRagnarok]

The walls have also never fallen out of character in the last few centuries or so. Imagine what mad roleplaying xp they get!