can you use "stonefire" to make a tunnel through a mountain?

[Recurver]

The Spell in question is called "stonefire" and it is in forgotten realms shining south book as a 5th level cleric spell.

Basically it burns a 5' square +1(5') square per 4 levels area on a wall made of stone and burns away 1 foot depth a round.

If i use persist metamagic on this spell making it last 24 hours it would burn through 14,400 feet of stone before it stopped (roughly 2.7 miles).

While this is extremely situational it seems very powerful for countries surrounded by mountainous terrain. did i miss something about this combo? or did i get it right that i can do this?

p.s. my GM allows range of touch to be used with persist spell

[Candlejack]

You would need to build support beams as fast as the spell clears out terrain, otherwise the tunnel would collapse. Stonefire seems best suited for creating holes in walls, rather than for making tunnels. The spell description itself even states that cave ins are likely to happen.

If you can find a way to prevent the tunnel from collapsing, your idea should work.

[Recurver]

You would need to build support beams as fast as the spell clears out terrain, otherwise the tunnel would collapse. Stonefire seems best suited for creating holes in walls, rather than for making tunnels. The spell description itself even states that cave ins are likely to happen.

If you can find a way to prevent the tunnel from collapsing, your idea should work.

Good point, If the shape of the initial area is under you direct control than you could fix that problem by simply keeping it small and have an arch at the top, then the stone walls themselves would support it. If all else fails i suppose i could get a lyre of building and follow 20+ feet behind it adding supports. The goal was to avoid having to get a lyre of building in the first place though because the lyre itself could do this(just not as fast).

[Fouredged Sword]

At 1ft a round it digs at a rate of 10ft a minute, or about .114 miles an hour. Burning for 24 hours means 2.75 miles, roughly. Supports are not your problem.

There is no way the air in the middle of a 2.7 mile shaft is breathable without ventilation.

A well manned crew of a few hundred men with precut supports could follow behind and hammer in supports faster than the fire can burn. Long tunnels will still be impractical.

[frogglesmash]

At 1ft a round it digs at a rate of 10ft a minute, or about .114 miles an hour. Burning for 24 hours means 2.75 miles, roughly. Supports are not your problem.

There is no way the air in the middle of a 2.7 mile shaft is breathable without ventilation.

A well manned crew of a few hundred men with precut supports could follow behind and hammer in supports faster than the fire can burn. Long tunnels will still be impractical.

A Bottle of Air™ and some creative thinking could probably solve that problem.

[Elkad]

There is no way the air in the middle of a 2.7 mile shaft is breathable without ventilation.

Opposite side of a mountain? Likely there is a pressure differential and there will be a wind howling through the tunnel. Which will occasionally change directions with major weather systems.


Oops, I mentioned physics in D&D. I'll report for punishment in the morning.

[Knaight]

Opposite side of a mountain? Likely there is a pressure differential and there will be a wind howling through the tunnel. Which will occasionally change directions with major weather systems.

That doesn't help until the mine is actually done.

As for once it is done, the mine shaft is essentially a plug flow reactor for the air in it. The pressure differential across the mountain pushes the air through continually from one end to the other, with the chemical concentrations at the entry point being that of outside air. Then you track a couple of key metrics (biomass, oxygen, CO2) as it moves through the PFR, and can take a look at how breathable the air is from that.

[Deophaun]

The question is why bother when you can just remove the mountain entirely with a lower level spell from the same book? (Rockburst)

[Zaq]

That doesn't help until the mine is actually done.

As for once it is done, the mine shaft is essentially a plug flow reactor for the air in it. The pressure differential across the mountain pushes the air through continually from one end to the other, with the chemical concentrations at the entry point being that of outside air. Then you track a couple of key metrics (biomass, oxygen, CO2) as it moves through the PFR, and can take a look at how breathable the air is from that.

So what you're saying is that we need to use warforged.

[Knaight]

So what you're saying is that we need to use warforged.

It couldn't hurt.

[Fouredged Sword]

You can also set your dig depth with dispel magic. I am pretty sure ypu can auto dispel your own magic, ending the effect and allowing your work crews a period of rest.

[Inevitability]

A Bottle of Air™ and some creative thinking could probably solve that problem.

Permanency'ed Gust of Wind is reasonably cheap (8270 GP) and moves approximately 7000 liters of air per round*, so that oughtn't be a problem unless you're moving many thousands of people through at once, and a 2.7 mile long tunnel would fit only something like 3000 people anyway.

*This assumes the spell moves all air molecules in a 5x5 foot square, the minimum area affected by the line, and that all air is moved at an average speed of least 10 ft. per second (the minimum speed for the spell to affect all creatures in its area within a round). If the spell's speed of 50 mph (approximately 7.3 times faster) is used instead, the amount of air moved is greatly increased.

[ayvango]

rockburst always would help you to deal with stone structures.
also you could use summoning to summon Thoqqua and made persist it with metamagic. It leaves usable tunnels after itself.

[Recurver]

I left for a weekend and came back to so much win that it brought a tear to my eye. Thanks all for your awesome posts, i very much appreciate it.

[Knaight]

rockburst always would help you to deal with stone structures.
also you could use summoning to summon Thoqqua and made persist it with metamagic. It leaves usable tunnels after itself.

Thoqqua are relatively small, from memory they're less than a foot in diameter. Even for ventilation shafts that's a bit small; for transportation tunnels it's downright unusable.

[noob]

Thoqqua are relatively small, from memory they're less than a foot in diameter. Even for ventilation shafts that's a bit small; for transportation tunnels it's downright unusable.

Make them dig multiple close tunnels.
Then anyway use rockburst on the planet because you hate the planet.
Then destroy what is left with voidstone warheads.
Then if there is still stuff left throw an orb of annihilation into a well of many worlds.
Restart on each and every plane.
That is totally the normal behavior for an adventurer

[weckar]

Make them dig multiple close tunnels.
Then anyway use rockburst on the planet because you hate the planet.
Then destroy what is left with voidstone warheads.
Then if there is still stuff left throw an orb of annihilation into a well of many worlds.
Restart on each and every plane.
That is totally the normal behavior for an adventurer

Well, I'd say digging a tunnel certainly is. Not sure about the mass destruction, otherwise.

[frogglesmash]

Well, I'd say digging a tunnel certainly is. Not sure about the mass destruction, otherwise.

What are you talking about? Mass destructive is the single most popular PC pastime.

[Angrith]

***Warning - Real Life Physics Below***

Supports shouldn't be an issue if you're digging this tunnel into the granite of the mountain. A 5'x5' or even 10'x10' hole should support itself just fine. Second, air might be an issue depending on the pressure gradient on either side of the mountain. Given a horizontal tunnel, the pressure gradient between sides of the mountain should provide air flow throughout the entire tunnel.

***DnD Rules Below***

From the d20 SRD

Slow Suffocation
A Medium character can breathe easily for 6 hours in a sealed chamber measuring 10 feet on a side. After that time, the character takes 1d6 points of nonlethal damage every 15 minutes. Each additional Medium character or significant fire source (a torch, for example) proportionally reduces the time the air will last. When a character falls unconscious from this nonlethal damage, she drops to -1 hit points and is dying. In the next round, she suffocates.

Small characters consume half as much air as Medium characters. A larger volume of air, of course, lasts for a longer time.

So the air in the middle of your 2.7 mile should be suitable for breathing for much longer than 6 hours given that it is a much larger volume. At 30' per round, you only need 0.8 hours to move through the entire tunnel. Therefore, I think we can conclude that bair won't be an issue either (assuming magical light sources instead of torches).