Slow Gas Trap

[Fenixcrest]

Here's a nice weird one. I have a feeling this might be moved to rules discussion for debate, but I thought I'd ask here first. I'm thinking of a trap to use in a Fantasy HERO dungeon, in which the facility is gradually flooded with a not-immediately-deadly gas like, say, helium, that will still suffocate you once there's enough saturation. The immediate thought would be to use the "holding your breath" rules, but by the time the PCs figure out what's up, it seems likely that they'll have been breathing and talking normally the whole time, especially if they're acting in character and think that the squeaky voices they have are due to some odd magic if the party alchemist fails his knowledge checks. The idea is that the dungeon builders planned for any would-be plunderers to be too deep into the tomb to escape suffocation by the time anybody catches on.

 

I guess the main question is, "should I skip directly to the suffocation rules once I decide the saturation has reached that point, or is there a gradual light-headedness to full-on inability to breathe scale that you recommend using?"

[Steve Long]

Re: Slow Gas Trap

 

This is definitely a discussion topic, so I've moved it.

 

My recommendation is that you just do it as a plot device and not worry too much about rules. However, springing traps on PCs without warning or a chance to detect them is No Fun. There should definitely be some clues as to what's going on -- a chance to make Smell PER Rolls, a feeling of lightheadedness they can diagnose with Paramedics, pet canaries keeling over, whatever -- so that they have a chance to avoid or mitigate the effects.

[Killer Shrike]

Re: Slow Gas Trap

 

A) Agreed, undetectable unavoidable Death Traps are generally not a good idea. Anyone remember Tomb of Horrors? {raises hand}

 

Gradual Effect.

[mwiggins]

Re: Slow Gas Trap

 

A) Anyone remember Tomb of Horrors? {raises hand}

No. what was it?

I've used some of "Grimtooth's traps" a few times, Ok, but too many unescapable instant death traps

[Killer Shrike]

Re: Slow Gas Trap

 

No. what was it?

I've used some of "Grimtooth's traps" a few times, Ok, but too many unescapable instant death traps

 

Tomb of Horrors

 

This is a D&D adventure created in 1978 for the purposes of testing the wit and fortitude of adventuring parties at game tournaments. "Testing" is used here in the same sense as the sentence "We'll be testing the dog for rabies." Let's just say the subject is not expected to survive the procedure.

—Lore Sjöberg of Wired on Tomb of Horrors.

[Sean Waters]

Re: Slow Gas Trap

 

I'm not sure how I'd build something like the trap you describe*, in fact I might not 'build' it at all - I'd probably just have the party make PER checks, or INT checks with some frequency to notice the effects. Almost any inert gas that 'replaces' the air is going to cause your torches to go out, so the trap is not undetectable (of course anyone using magical lighjt that does not rely on oxggen to burn might be in more trouble, but even then they should begin to notice the effect it is having on them.

 

BTW, CO2 is probably an easier gas to 'manufacture' than helium, and should work just as well. You can produce plenty by dropping acid onto limestone. Although it doesn't cause odd voice changes (helium, being light, would tend to float up through the dungeon come to think of it) it is detectable as concentration increases by the burning sensation you get as it dissolves in the eyes and mucous membranes - so is still detectable even if you don't know what you are detecting. CO2 is about 1.5 times denser than air so will accumulate in pits or the lower levels of a dungeon.

 

Mind you there should be some way around it. I'd suggest that (once detected) the party can hold their breath and run through the affected area. Alternatively you'd need some sort of magic or technology to circumvent it. It could be as simple as opening a vent which allows the gas to disperse. Also CO2 is solule in water so you might get rid of a lot of it by spraying the area down.

 

 

 

*We've had lengthy discussions on how you build 'suffocation' as a power and what I've carried from those dicussions is this: it is pretty much not worth it. If you really feel the need, you might want to use 'change environment'.

[Sean Waters]

Re: Slow Gas Trap

 

A) Agreed, undetectable unavoidable Death Traps are generally not a good idea. Anyone remember Tomb of Horrors? {raises hand}

 

Gradual Effect.

 

**raises hand** That takes me back...

[Ockham's Spoon]

Re: Slow Gas Trap

 

Undetectable gas trap is a another way of saying "the GM kills you all by fiat". But I think that undetectable misses the point for such a trap, which is to heighten the tension of the party "Holy Excrement! We have to get out of here fast before we succumb to the gas!" For that reason alone they should have some idea of what is happening. You might build it with Invisible Power Effects so that technically they wouldn't know what was going on, but then give them an INT check or appropriate KS roll to figure out why their STN was slowly disappearing.

 

_______________________________________________________________________

"I'd say you boys have had enough beans already! Phew!" - Slim Pickens in Blazing Saddles

[Sean Waters]

Re: Slow Gas Trap

 

Undetectable gas trap is a another way of saying "the GM kills you all by fiat". But I think that undetectable misses the point for such a trap, which is to heighten the tension of the party "Holy Excrement! We have to get out of here fast before we succumb to the gas!" For that reason alone they should have some idea of what is happening. You might build it with Invisible Power Effects so that technically they wouldn't know what was going on, but then give them an INT check or appropriate KS roll to figure out why their STN was slowly disappearing.

 

_______________________________________________________________________

"I'd say you boys have had enough beans already! Phew!" - Slim Pickens in Blazing Saddles

 

I remember a DnD scenario with poison gas. It was 8-10th level or somesuch and you basically lost 1HP per turn, lending a certain urgency to proceedings, but not being immediately threatening (you could stop the damage by leaving the dungeon).

 

As a dramatic device it can work well, but obviously no one is advocating telling the players: You all start speaking in high pitched voices, hallucinating and, half an hour later, you are dead. Create new characters please...

 

At least I hope they are not

[Roy_The_Ruthles]

Re: Slow Gas Trap

 

I played through a 3.5 port of Tomb of Horrors. The trick here was we all had as rediculously defensive characters as possible and were all paranoid dudes. We were like "oh, a sphere of annihilation instead of a door, there must be some way for us to turn this into a cash system, but let us continue into the fake floor lava room instead"

[Fenixcrest]

Re: Slow Gas Trap

 

I'm back to participate

 

Okay, so my plan wasn't really for unavoidable total party kill haha. That would just be the plan of whoever built the dungeon. I'm just wondering what the appropriate mechanic for increasingly urgent suffocation is, and whether that type of thing should, at first, anyway, be made statistically transparent to PCs.

 

"The air seems sort of weird here. You feel fatigued, and suffer from Long Term Endurance effects..." I feel like that should probably happen before the hallucinations and death, but the problem is as stated above in the Tomb of Horrors comments: veteran PCs are accustomed to paranoia. I foresee the first game-mechanic clue of a toxic atmosphere, maybe the second one, would incline my group to abandon tomb and return to town without their McGuffin. Heaven forbid they bring a canary with them, or something.

 

TL;DR version: when does, "OH NOES IT'S THE AIR ALL AROUND US" become part of the description of the weird sensations the party is experiencing, in your opinions?

[Sean Waters]

Re: Slow Gas Trap

 

I'm back to participate

 

Okay, so my plan wasn't really for unavoidable total party kill haha. That would just be the plan of whoever built the dungeon. I'm just wondering what the appropriate mechanic for increasingly urgent suffocation is, and whether that type of thing should, at first, anyway, be made statistically transparent to PCs.

 

"The air seems sort of weird here. You feel fatigued, and suffer from Long Term Endurance effects..." I feel like that should probably happen before the hallucinations and death, but the problem is as stated above in the Tomb of Horrors comments: veteran PCs are accustomed to paranoia. I foresee the first game-mechanic clue of a toxic atmosphere, maybe the second one, would incline my group to abandon tomb and return to town without their McGuffin. Heaven forbid they bring a canary with them, or something.

 

TL;DR version: when does, "OH NOES IT'S THE AIR ALL AROUND US" become part of the description of the weird sensations the party is experiencing, in your opinions?

 

Canaries? That is what rogues are for

 

You could easily enough have a construct like this:

 

Suffocation: 40 active and real

Drain REC, END, STUN, BODY 0 1/2d6, any REC/END/STUN/BODY power one at a time (Can only drain REC if there is any, then has to drain END, STUN, finally BODY in order; +1/4), MegaScale (1" = 200m; +1/4), Uncontrolled (+1/2), Reduced Endurance (0 END; +1/2), Delayed Return Rate (points return at the rate of 5 per Hour; +1), Continuous (+1), No Normal Defense (LS: Self contained breathing or an air supply; +1), Invisible Power Effects, SFX Only, Hide effects of Power (Fully Invisible; +1), Area Of Effect (3" Radius; +1), Conforming (+1/2) (40 Active Points); Limited Power Power loses about a third of its effectiveness (Effect only starts when target's REC = 0; -1/2)

 

That effectively reduces characteristics by 2 character points per phases on average, or about 1 REC per phase (then 4 END, 2 STUN and 1 BODY). Once the REC is gone, it starts on END then STUN then BODY. If you have 10 REC, 50 END, 50 STUN and 20 BODY you'll last about 10+13+25+20 = 68 phases before you start dying real quickly (i.e. before you get to 0 BODY), which is about 13 1/2 minutes, assuming you don't do anything else at all but reduce your SPD to 1 and lie there. What are the chances?

 

The power is megascale so it covers an 600m radius (conforming), so can flood whole corridor complexes (you can dial that back as much as you need to) - and dial it up to a 3km radius area for the same cost.

 

The sfx and effects are invisible, but the source is not (I figured on whist mist pouring through vents set in the walls) - the PCs will see that some sort of gas is coming in to the area but it is not going to have an immediately obvious effect on them.

 

The recovery rate is such that you only get back 5 per hour, and no one is going to live that long. You can add in a limitation that the drained characteristics recover faster than 5/hour once you are out of the cloud, if you like, and as it is uncontrolled there are ways of turning it off ( stopping up all the vents or some sort of chemical reaction possibly).

 

If they don't notice before, PCs should cotton on when they start burning STUN for END. You might want to have some creatures down there adapted to the low O2 conditions to chase them about: they might also notice when they stop getting PS12 recoveries!

 

Anyway, if you want to build it there you have one possibility.

[Ternaugh]

Re: Slow Gas Trap

 

Tomb of Horrors

 

This is a D&D adventure created in 1978 for the purposes of testing the wit and fortitude of adventuring parties at game tournaments. "Testing" is used here in the same sense as the sentence "We'll be testing the dog for rabies." Let's just say the subject is not expected to survive the procedure.

—Lore Sjöberg of Wired on Tomb of Horrors.

 

Here's the link to download the adventure (revised for D&D 3.5) for free from WOTC:

 

http://www.wizards.com/default.asp?x=dnd/oa/20051031a

 

JoeG