Falling Into Lava

Ah, lava. The ultimate expression of nature’s destructive power. The awesome force of annihilation that is the antithesis to the equally amazing force of life. The doom of thousands throughout history. The peril that every fantasy in the history of fantasy utterly fails to represent in any manner close to realism.

In this article, we will look at the science of lava and why it is such a dangerous hazard to use in your game. We will also provide recommendations for how to avoid downplaying the dangers associated with it and, hopefully, encourage your players to not tempt their chances at this article’s name.

Pedantic Preamble

Let’s first establish some terminology. Magma is molten rock that lies beneath the Earth’s surface. Lava is magma that has been forced above the surface where it rapidly cools. The two terms refer to the same substance in popular culture, and so throughout this article we will use ‘lava’, except where it is specifically understood to be in reference to underground molten rock.

How Hot Is Lava?

Lava is hot. We mean, really hot. Lava flows can get as high as 1,600°F, while magma can reach 2,120°F. For comparison, skin burns in under a second at 160°F (you will suffer third degree burns after two seconds immersed in 150°F water). The highest survived internal body temperature was 115°F.

Now, we’re talking about molten lava here. By that, we mean the bright stuff, not the cooler crust that forms atop slow-moving lava flows as the heat radiates out and the rock returns to a more solid state. Lava with such a ‘skin’ is probably closer to 500°F, and the only person in history to ever have fallen into lava and survived had the dubious fortune to have fallen into such a flow. This state of lava, being something which a particularly lethargic turtle could outrun, is virtually never encountered in adventures, which favour the dramatic over the realistic, and so we are not going to bother discussing it in this article. What we are talking about in this article are bright, orange flows—the stuff of epic fantasy.

Approaching Lava

There are a few important factors to consider when approaching lava.

  • The angle of exposure (“How much lava do you see?”)
  • The temperature of the lava
  • Air flow
  • The reflectiveness of what you’re wearing
  • Toxic fumes

Let’s set aside the fact that the hydrogen sulphide gasses from a volcanic flow are likely to kill you before you can fall into the lava itself and instead just focus on the heat. (As much as we like to be realistic, we realize that the toxic fumes are not why you’re here. You want to know how hot it gets so you can make an informed decision about the damage to roll, so let’s get to it.)

The heat flux from an object (in this case, a lava flow) drops as the square of distance, so as you get closer and closer it will get exponentially hotter. At a distance of 94 million miles, the intensity of the sun’s light on Earth is one thousand watts (1 kilowatt) per square metre, or 1 kW/m². For a typical lava flow (say 1,300°F), you would experience the same heat by approaching within 30 feet at a 10 degree angle to the lava, and an average (5’9”) person who approaches within 6 feet of lava at just a 50 degree angle will be feeling the heat of 25 suns directly on their face.

So, when designing encounters that include lava, be sure to deal fire damage to players stupid enough to approach within 30 feet of it. And, when placing bridges over lava, don’t place them at a height of only 5 feet (like Wizards of the Coast has done on numerous occasions…). At least, not if you don’t want your PCs to instantly suffer severe burns. To make it simple, here are our very simplistic suggestions:

  • Within 30 feet of lava, a creature takes 1d4 fire damage per round. Even at this distance, the skin becomes visibly flushed with exposure. Unless you have fire resistance, the heat causes your eyes to water, imposing disadvantage on attack rolls and Wisdom (Perception) checks based on sight. At the beginning of every round that the creature is exposed to the lava, they must succeed a DC 10 Constitution saving throw or suffer 1 level of exhaustion. These effects are negated if the character ducks down or avoids exposing themselves to the lava.
  • Within 20 feet of lava, a creature takes 1d10 fire damage per round unless they crouch down (half movement speed). Exposed skin suffers second-degree burns that take 2d6 days to heal without magical healing. At the beginning of every round that the creature is exposed to the lava, they must succeed a DC 15 Constitution saving throw or suffer 1 level of exhaustion. Creatures wearing medium or heavy armour, or who are clad in heavy clothing, have disadvantage on the saving throw. Creatures with resistance or immunity to fire damage automatically succeed on the saving throw.
  • Within 10 feet of lava, a creature takes 4d10 fire damage per round unless they crouch down (half movement speed). Exposed skin suffers second-degree burns that take 3d6 days to heal without magical healing. At the beginning of every round that the creature is exposed to the lava, they must succeed a DC 20 Constitution saving throw or suffer 1 level of exhaustion. If the creature was not holding their breath, is wearing medium or heavy armour, or is clad in heavy clothing, they have disadvantage on the saving throw. Creatures with resistance or immunity to fire damage automatically succeed on the saving throw.
  • Within 5 feet of lava, a creature takes 20d10 fire damage per round, or half as much if they lie prone (they can crawl 10 feet per round). Under direct exposure, cloth garments burn away, metal armour sears to flesh, and exposed skin suffers third-degree burns, causing permanent disfigurement to exposed extremities. The DM determines the nature of this disfigurement (the Lingering Injuries table in the Dungeon Master’s Guide has some great suggestions). At the beginning of every round that the creature is exposed to the lava, they must make a DC 25 Constitution saving throw. On a success, they suffer 1 level of exhaustion. On a fail, they are reduced to 0 hit points. If the creature was not holding their breath, is wearing medium or heavy armour, or is clad in heavy clothing, they have disadvantage on the saving throw. Creatures with immunity (but not resistance) to fire damage automatically succeed on the saving throw.

The idea of a ‘safe’ distance to cross over lava is really somewhat paradoxical, not only because heat rises but also because molten magma can bubble, creating jets that spray up dozens of feet. Nonetheless, creatures with resistance or immunity to fire may build their homes in proximity to molten magma, which may require building bridges or platforms above the flows that can provide for an impressive setting for a fight scene.

With sufficient air flow, an adventurer could possibly survive crossing a bridge sufficiently high above magma, especially if it is a stone bridge with solid side-guards that offer some protection from the direct heat. When designing dungeons that adventurers could survive, we suggest placing such bridges at heights of at least 60 feet (if the bridge is exposed to open air that cools the surrounds) or 90 feet (if the bridge is located in an enclosed cavern). If the structures would take adventurers closer, we suggest using the same guidelines laid out above, doubling the distance at which damage scales (if in open air) or tripling the distance at which damage scales (if in an enclosed cavern). For example, an open-air bridge within 60 feet of the lava flow or a bridge in a cavern that is within 90 feet of a lava flow would result in the adventurer suffering 1d4 fire damage per round.

Falling Into Lava

At last, we come to the question that most likely brought you here: what happens if you fall into lava?

Now, this section should be prefaced with the caveat that nobody actually knows for sure. This is, rather understandably, not a very well-studied occurrence. It’s hard to get people interested in an experiment in which they will most likely suffer grievous personal injury, if not simply being outright incinerated. Because of a lack of volunteer lava swimmers, much of what we understand of the effects of sudden, intense heat is either from those few eyewitness accounts to the heat wave of nuclear attacks such as at Hiroshima and Nagasaki, or from examining the remains of pyroclastic flow victims, such as those entombed in volcanic ash at Herculaneum and Pompeii. Additionally, physics being what they are, we can make several educated guesses to supplement the existing research.

First of all, let’s be absolutely clear about something that the Dungeon Master’s Guide has lied to you about for years: if you do not have immunity to fire and you fall into lava, you’re just dead. No death saves, no damage rolls, just instant death. Good bye. Only true resurrection or a wish spell can bring you back now. Don’t believe me? Well, fortunately, I am prepared to guide you through the macabre details of what we understand would occur.

For starters, you wouldn’t fall into lava, you would fall onto lava. Lava is molten rock, three times denser than water and at least 100,000 times as viscous; unless you were falling from a great height, the lava would deform under your weight, but you wouldn’t break the surface. If you were to somehow stay there for a while, you might eventually be subsumed by the molten rock. Unfortunately, you would be much too busy being vaporized for this to happen. No, I don’t mean that in a hyperbolic sense.

Have you ever seen a drop of water fall on a hot skillet? Have you seen how it steams, dances, and sizzles? This is called the Leidenfrost Effect, and that drop of water would be you. Your skin would rupture, blacken, and evaporate (going from solid to liquid to gas) so quickly that it would actually cushion your impact against the lava before scattering you across the walls of whatever lava tube or channel you’ve fallen into. Pieces of you would fly in different directions before incinerating into ash.

And if that weren’t enough, as you are destroyed from the outside, you’d be getting destroyed from the inside, as well. Your body, which is made of 60% water (an excellent thermal conductor), would literally boil inside. Your organs would rupture, your bones would crack, your blood would turn to gas inside your veins. Just for good measure, your brain would probably boil so quickly that the pressure would blow your skull apart.

See what I mean when I say “you’re just dead”? There is no quantity of dice to approximate how dead you are at this point. The answer is simply, “Yes”.

Conclusion

Lava is by far one of the most dangerous perils an adventurer will ever encounter, more deadly even than the breath of an ancient red dragon. In spite of this, every official adventure invariably downplays the risk it poses. Whether by giving you grated metal bridges to cross a whole 5 feet above the lava flow (Tomb of Annihilation) or suggesting a mere 6d10 damage for wading into molten magma (Princes of the Apocalypse), it is almost as if Wizards of the Coast (or any movie director in the history of Hollywood movies that inspire them) has never attempted to learn anything about this deadly hazard. In point of fact, both of the situations described above would spell instant, gruesome death for anyone who doesn’t have immunity to fire damage. Lava. Is. Deadly.

The next time you want to include lava in your campaign, try putting your head into your oven when it’s turned up to 400°F. Now imagine if your oven was five times hotter. That’s the hazard you’re throwing at your PCs. It’s not ‘very hot water’ that can be easily waded through, it’s ‘molten death’. Try to impart that to your players. Tell them that, even from dozens of feet away, their characters are being overwhelmed by the heat. Make it a frightening experience, sell them on the danger. They will appreciate the encounter all the more for it. And if they fall in… well, they won’t ever make that mistake again.


Have you ever used lava in an encounter? Did you follow the suggestions of the rules, or did you play it straight? Let us know below!


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13 thoughts on “Falling Into Lava”

    1. Hi Kitty,

      Tieflings have resistance to fire damage, not immunity to falling into molten rock. My verdict would be death.

      Best,
      – the Archmage

  1. Thank you for writing this, I am going to use it in my upcoming campaign. It’s really helped me rethink how I am introducing lava and heat in the game.

    That said, I would love to see an article like this on extreme cold, falling into frozen lakes, etc.

  2. Great stuff. Reading this over really gave me a good base for a game coming up soon.

    I’ll be DMing a session within Hrakhamar from ToA, a forge within an active volcano. In my game, the mere atmosphere within the forge is decidedly *deadly* — the ambient temperature is 400+ degrees, and the air is saturated with toxic fumes. I made the red dragon nearby, Tzindelor, an adult dragon — meaning its proximity alone opens unstable gates to the elemental plane of fire.

    Oh, and the whole cavernous structure is placed 120+ feet above the magma flow now xP

    Of course, all this is based on the deadly scale that I have found in this resource here! Looking forward to seeing what my players do to counteract these dangers. Naturally I’ll be enhancing the quality of the forge’s treasure to scale with the epic dangers found within.

  3. So, in a dungeon built into a volcano, there’s a forge attended by creatures called magma corpses (basically lava zombies). Literal streams of lava cut through the center of the forge, which is only about 30 feet across. The PCs can’t just ignore it, however, because if the magma corpses see them, they can flee into a giant series of mine tunnels to warn even worse guys.

    They should be thankful for that House Jorasco outpost nearby.
    (Just wondering, what would happen if something immune to fire damage fell in?)

    1. Also, how much damage do you think being hit by a glob of lava (being thrown by the same magma corpses) would deal?

      1. Thank you for your question!

        As I laid out in this article, molten lava is 10 times hotter than what is needed to burn skin in under 1 second. If it actually hits someone, they’re going to simply die. When describing such an attack, therefore, I suggest that you represent ‘hits’ as near misses that required the character to dodge desperately, possibly leaving themselves off balance or banging into something, rather than have a character take a faceful of lava and somehow keep going.

        As to how much damage the attack should deal mechanically, you should be able to determine an appropriate amount of damage for the party’s level following the suggestions in the Creating a Monster section in chapter 9, “Dungeon Master’s Workshop”, of the Dungeon Master’s Guide. The Creating Encounters section in chapter 5, “Creating Adventures”, in the Dungeon Master’s Guide can help you determine how tough the creatures should be to provide the desired challenge to the party (an easy encounter, a hard encounter, a deadly encounter, etc.).

        Enjoy!
        – the Archmage

  4. This is a great read. Putting my “make the game fun and playable” hat on though I’m going to have to further simplify the effects in my game, as 4 tiers of 3 effects is fairly complex for a game intended to abstract physics 🙂

    I’d love your thoughts on what a simpler-yet-still-somewhat-realistic rule set would be.

    1. Hi Joel,

      A three-tier, 30-feet/15-feet/5-feet scale could work.

      I opted for four tiers because it worked for my players. They didn’t try getting within 10 feet of the lava, having learned between 30 feet and 20 feet and receiving second-degree burns that it was a bad idea to continue, thus sparing themselves taking many times the amount of damage and yet another exhaustion level. But if they did approach within 10 feet, the damage was high enough to render them unconscious as opposed to kill them outright.

      Perhaps I’m too merciful. Be sure to share the results of your own system!

      Best,
      the Archmage

  5. What happens if someone has Death Ward on them and falls in lava? I’m about to DM a 5e campaign, but I’m not sure if the lava would kill them or not.

    1. Hi Jonathan,

      Thanks for your question!

      This is one of those “That’s Nice, But It Doesn’t Matter” situations. There are too many forces that would potentially kill someone—the fall, the heat, the toxic fumes. I’d let someone with death ward survive only until the start of their next turn. If somehow they’re miraculously rescued before then, fantastic! Otherwise, they’re dead and beyond any rescue save by true resurrection.

      Best,
      the Archmage

  6. I did really enjoy the read, however I do have 2 critiques.

    1. The hp of a normal human being is 4, so for normal people being punched by an immensely strong creature, all poisons (I can think of) and here, standing 30ft from Lava is a very good chance of instant death. This is the same for most humanoid creatures in DnD (at lower CRs and Levels). So it’s not like WotC have made it less dangerous against normal people.

    2. Adverturer’s are bonkers, and I’d love to hear your thoughts on the spell water walk and Lava. The PHB says you don’t take damage from the Lava itself, but you still do from the heat of it.

    1. Hi Bob,

      Thanks for your comment!

      I never noticed that water walk allowed someone to walk over lava. I suppose if you have immunity to fire damage this would be useful should you find yourself needing to stand atop molten lava for long enough that you might otherwise begin to sink. Really, it just demonstrates that the developers are using pop culture notions of what lava is and how it behaves.

      As for the damage, it says you treat it as harmless solid ground, which is extremely perplexing. Lava and acid would melt or dissolve nonmagical shoes, and unless you have a Superman suit, you’ll arrive at the end of a stroll across a lake of lava as a naked fire immune creature. Not even steel is likely to survive exposure of more than 1 minute to the intense heat before it begins melting.

      The whole point of this article was to establish that pretty much everything in the rulebooks about lava should be thrown out. To date, I still have yet to see anything lava-related in D&D that makes sense.

      Best,
      the Archmage

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