Red dragons and lava (3.5)

[Seharvepernfan]

Could a red dragon (who lives in a stone cave somewhere non-volcanic) create lava in or near his lair with just his fire breath? How long would it stay lava-hot? Could he make a tunnel of lava through the stone? Or would the heat just diffuse evenly?

I realize that these are science-based questions not covered by the rules, but I figured this would be a good place to ask.

[Qc Storm]

Fire has a hard time damaging stone. A dragon old enough to "melt" rock could probably just use spells instead.

[hamishspence]

I'd probably rule that to turn rock into lava, you need to do enough fire damage to a rock section, to "destroy" it.

A 5 ft thick, 10x10 foot section of unworked stone, would have 900 HP and Hardness 8:

http://www.d20srd.org/srd/dungeons.htm#walls

and fire damage does half damage to objects before applying hardness.

As to how long it would take to cool- I remember reading that a 1 ft thick layer of lava takes a month to cool fully, and a 3 ft thick layer takes a year.

[Seharvepernfan]

Fair points, but the damage dealt would "stick" right? So the dragon could just keep at it for a few hours and make a bunch of lava.

[One Step Two]

Math!

Assuming an Adult Red Dragon:

12d10 Fire Damage every 1d4 rounds. So 66 average damage every 2.5 rounds (15 seconds)
Halve and Less 8 damage for hardness. The dragon can apply 25 Damage every 2.5 rounds
It would take 36 average attacks total to deal over 900 damage, in an average of 90 rounds.

8-15 minutes of warning, and a dragon can make a nice patch of lava to deter entrants. Not too shabby.

Edited to reflect halved damage.

[hamishspence]

True. Complete Arcane has a 9th level Transmute Rock to Lava spell- but the lava transmuted, though it cools naturally, cools rather fast.

After 2d6 hours, it no longer does fire damage.

After 2 days, a 1.5 ft thick layer is cool right through.

Though it takes over a month for a 10x10x10 ft cube to cool all the way to the centre.




4-10 minutes of warning, and a dragon can make a nice patch of lava to deter entrants. :smallbiggrin:

Don't forget objects take half damage from fire before applying hardness.

[One Step Two]

Tsk, I knew I was forgetting something, Editing.

[TuggyNE]

12d10 Fire Damage every 1d4 rounds. So 66 average damage every 2.5 rounds (15 seconds)
Less 8 damage for hardness. The dragon can apply 58 Damage every 2.5 rounds
It would take 16 average attacks total to deal over 900 damage, in an average of 40 rounds.

Well, fire damage is halved against most objects (and stone needn't be an exception) so it would take considerably longer at the corrected rate of ~10/round. 90 rounds, in fact, making an average of 36 breaths.

Still, doesn't take too long.

[ericgrau]

Could a red dragon (who lives in a stone cave somewhere non-volcanic) create lava in or near his lair with just his fire breath? How long would it stay lava-hot? Could he make a tunnel of lava through the stone? Or would the heat just diffuse evenly?

I realize that these are science-based questions not covered by the rules, but I figured this would be a good place to ask.

His breath would have to be as hot as lava and even then due to the small area the heat would quickly dissipate into the surroundings. You need a source of heat that is both incredibly intense and in a huge area, in the hundreds or thousands of feet across, to pull it off.

Lava does 20d6 fire damage per round to those in it, so that could help you ballpark the intensity

[Crake]

His breath would have to be as hot as lava and even then due to the small area the heat would quickly dissipate into the surroundings. You need a source of heat that is both incredibly intense and in a huge area, in the hundreds or thousands of feet across, to pull it off.

Lava does 20d6 fire damage per round to those in it, so that could help you ballpark the intensity

to be fair, 20d6 and 12d10 have the same maximum, while 20d6 has a slightly higher average of 70, vs 12d10's 66, so it's pretty close

[One Step Two]

The problem is in how constant the heat is being applied. Because the average re-charge time of the breath weapon is 2.5 rounds, that's 15 seconds of heat dissipation. Now, before we start killing cat-girls, it's note-worthy to mention that in many classical fictions, the breath of truly powerful dragons can warp and melt stone.

The "lava" created would certainly be temporary, or, at the very least make a passage very difficult to cross.

If nothing else, if a (forewarned) dragon wanted to take some time to make the passage to his hoard extreemely hot, I'd call it something like Uneven Flagstones (http://www.d20srd.org/srd/dungeons.htm#floors), and add that it's sizzling hot, and possibly amoprhus surface (doing 2d6 fire per round, like proximity to lava), is like Dense rubble.

[karkus]

Hardness doesn't apply to energy damage, though. Only physical damage is reduced.

[Yora]

It would also depend on the type of rock. Melting granite would be quite difficult, but sedimentary stone should be a lot easier to melt. Limestone can be destroyed by temperatures of about 1000°C, which should be possible for dragon fire. But it wouldn't be lava and cool just as quickly as it heats up.

[Fouredged Sword]

This could make a particularly nasty trap though. The surface would cool very quickly after the dragon stopped breathing, but the under layer would stay very hot for several minuets, as the top layer would insulate it like ice on a pond. A Smart dragon could make shallow covered lake of lava. The top would just be rock, and if the players didn't stop to wonder why the floor is burning hot the run out over it to fight the dragon.

The dragon then puts it's foot through the rock distabalizing the surface dropping everyone into the lava. The dragon then forcewalls the surface so you drown even if you have fire immunity, or hits the lava with a cold spell to freeze the lava, encasing you in rock.

[Bakeru]

Hardness doesn't apply to energy damage, though. Only physical damage is reduced.There's a lot of discussion if hardness applies to sonic and/or acid, but the SRD is pretty clear that all other elements have to deal with hardness.

[Starbuck_II]

Hardness doesn't apply to energy damage, though. Only physical damage is reduced.

You are thinking of DR. Hardness is better.

[herculesftw]

Lets not forget how much strength a Red Dragon has. That could serve a great leeway to break down weakened rock, quickening the magma

[dascarletm]

This could make a particularly nasty trap though. The surface would cool very quickly after the dragon stopped breathing, but the under layer would stay very hot for several minuets, as the top layer would insulate it like ice on a pond. A Smart dragon could make shallow covered lake of lava. The top would just be rock, and if the players didn't stop to wonder why the floor is burning hot the run out over it to fight the dragon.

The dragon then puts it's foot through the rock distabalizing the surface dropping everyone into the lava. The dragon then forcewalls the surface so you drown even if you have fire immunity, or hits the lava with a cold spell to freeze the lava, encasing you in rock.

well, now my players are going to hate me when they fight their next red dragon.:smallamused: