Dungeon Master Assistance

A place to share thoughts and ideas about Dungeons and Dragons

D&D 5E – House Rules for Lava


Lava Should NOT be Realistic.

My first inclination was to make the rules regarding lava as realistic as possible but eventually gave up. I have decided to not even try to make lava in D&D realistic. Here is why.

As I see it, you have two different options when coming up with house rules for lava in your D&D games. You can try to make interactions as realistic as possible or you can give it more of a fantasy feel. As an example, here are two different ways I might come up with house rules for falling into lava.

Falling into Lava (2 options)

Option 1 – Reality

  1. In the first second falling towards the lava, the air temperature rises to 200 degrees Fahrenheit. At this point any exposed skin will immediately blister. It feels as though every inch of your skin is touching a hot stove.
  2. You fall for another second toward the lava, and now the air temperature has doubled to 410 degrees. At this point your hair and any clothes you were wearing ignite into flames.
  3. A second or two later you approach the surface of the pool of lava which is between 1200 – 2500 degrees Fahrenheit. You lose consciousness from the immense pain as your flesh is charring, your blood and fluids are boiling.
  4. You begin to asphyxiate as your lings are charring due to the hot gases above the surface.
  5. The superheated air is burning your lungs filling them with fluid much like a blister from a burn fills with fluid.
  6. You are have a cardiac arrest before you ever touch the lava. Your brain isn’t registering much if anything at all at this point.
  7. As you get closer to the lava the water in your body rapidly turns into steam, causing your cells to burst and rapidly swell your body. The pressure from the created steam passes the amount of pressure that your skin and muscles can tolerate, and they begin to tear apart – either in an explosion, or by creating large openings for said steam to escape.
  8. As your skull gets closer to the lava, the water inside your brain behaves similarly, causing your head to explode as the pressure from your brain boiling alive goes above the threshold of what amount of pressure pushing outward your skull can contain.
  9. When hitting this super dense substance at a high speed you may break your neck or crack your skull open.
  10. Then, resting on a bed of molten rock four times hotter than the broiler in an oven, you quickly burst into flames.
  11. In the blink of an eye, it is just your bones and ashes on top of the lava.
  12. Your bones are all burned to ash a few seconds later.

D&D reality house rule: If you fall into lava you die. No saves.

Option 2 – Fantasy

  1. You can sink into the lava like Gollum does in the movie “Lord of the Rings: Return of the King.”
  2. Lava should be scary and potentially lethal but possibly survivable, like falling form impossible heights. Some examples where D&D rules aren’t very realistic:
    1. Fireball damage: The fireball spell does 8d6 fire damage on a failed save, or half as much damage on a successful one. Objects that are worn or carried are not affected.
    2. Falling damage: A creature takes 1d6 bludgeoning damage for every 10 feet it falls, to a maximum of 20d6.
    3. Power Word Kill: This spell has no effect on creatures with more than 100 hit points.
  3. Also, lava would not make a good backdrop for an encounter if it was strictly realistic.

D&D fantasy house rule: Any creature that falls into lava or starts its turn there takes 55 (10d10) fire damage.

Here are the rest of my house rules regarding lava (these apply to magma as well). Whether it is because lava is different or for some other reason it is just more “fun” if works like this.

How lava behaves (in my fictional D&D world)

  1. You can think of lava as being similar to thick oatmeal that is extremely hot.
  2. Crust: It doesn’t normally form a “crust”.
    1. As long as it is in motion the surface stays liquid, hot, red, and glowing but there may be exceptions.
    2. When it stops moving and pools up it will form a crust after cooling for 24 hours. (It cools twice as fast if underwater.)
    3. The crust is 1 foot thick and does 1d6 fire damage per round to any creature that walks on it.
    4. After 10 days the crust will be 2 feet thick and no longer does fire damage when you walk on it.
    5. The crust continues to thicken one additional foot every 10 days until the lava all becomes solid stone.
  3. Lava rate of flow: It flows slowly enough that you can normally avoid it. Lava flows at 5 ft. per round (50 ft. per minute, 1/2 mph). This is the same at any angle or over any terrain, even straight down without any support.
  4. Swimming in Lava: Swimming speed in lava is 1/4 your walking speed, or 1/2 your swim speed.
  5. Walking on Lava: Even if you are immune to fire, you can’t walk on the surface without magic, such as the “Walk on Water” spell.
  6. Wading through Lava: If the depth of the lava is not above your shoulders you can wade through it. When wading through it, if its depth is no higher than your knees it is treated as difficult terrain, otherwise your speed is reduced to 1/4 of your walking speed..
  7. Immunity to Lava: An immunity or resistance to fire serves as an immunity or resistance to lava. However, a creature immune to fire might still drown if completely immersed in lava.
  8. Gasses: Lava doesn’t normally also have toxic or dangerous gasses emanating from it.
  9. How it spreads: When it reaches a relatively flat surface it will spread. As an example, in one round a 5 foot cube of lava will spread to fill 5 random adjacent 5 ft. spaces to a depth of 1 foot. Lava that is only 1 foot deep no longer spreads unless more lava is added.
  10. Damage:
    1. Being Close: When a creature enters to within 10 feet of the lava, or starts its turn there, it takes 1d6 fire damage due to the heat radiating off the lava. It takes this same damage if it is using the “Water Walk” spell to walk on the surface of the lava.
    2. Wading: A creature takes 5d10 fire damage each round when wading through a lava stream
    3. Falling In: Any creature that falls into the lava or starts its turn there takes 55 (10d10) fire damage.
    4. Objects: Any object that isn’t being worn or carried takes fire damage as a creature does. An object that is reduced to 0 hit points from taking fire damage from lava is completely destroyed.
    5. Dying: A creature that is reduced to 0 hit points from taking fire damage from lava is disintegrated and everything it is wearing or carrying is completely destroyed (no saving throw, no death saves).

Note: the damage is less than indicated in the DMG but I have added the no death saves and destroying all objects rules.

2 responses to “D&D 5E – House Rules for Lava

  1. Ravi April 25, 2022 at 12:49 pm

    Thank you, I will never go to Hawaii now. :/

    Liked by 1 person

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