D&D General Is this a fair trap?

[Ruin Explorer]

Isn't this answering - is the tap plausible or good - rather than is it fair?

They're the same thing.

If you have a trap that wouldn't function, and shouldn't function, and you as the DM let it function, simply because some dude in 1980 had a terrible grasp on basic day-to-day physics and had forgotten Yellow Molds were insta-killed by fire, that would obviously be completely unfair on the players.

So having the trap function correctly is deeply unfair.

If you made it into a hilarious fail, which how it should actually work, then it wouldn't be unfair. Really if it's played honestly, it's going to fail one of two ways:

1) The players are suspicious as hell of the entire setup (as they should be) and easily discover the GC and kill it, and either move on or get it out and get at the treasure.

or

2) Fire gets involved in some way, and the trap basically self-destructs. There's just no plausible way the Yellow Mold doesn't catch on fire if the GC and rope are on fire. You'd be lucky if the Yellow Mold didn't go so deep into the GC that it detonated there anyway! Safely containing the spore.

So again it is unfair for the trap to WORK. This is an issue with a fair number of older traps in D&D. They were clearly written up by people with a tenuous grasp on physics and/or cause and effect, and not thought through at all.

 

[NotAYakk]

There are a few ways to interact with a trap, gameplay wise.

1. You are playing "mousetrap" the board game. There is a Rube Goldberg device whose default end result is probably "you die" in the room. Get the cheese.

2. You are in a fantasy world that makes sense. Some being has set up a deadly device for a purpose here, and that purpose makes sense. You have a goal, and this device is in the way.

This is a "boardgame" style trap. If that is your social contract with the players, sure, this is a Rube Goldberg device that can kill and can be defeated by a paranoid group of PCs. Fair enough.

However, it basically makes no sense in any reasonable fantasy world, as the effort to build and maintain this device is simply ridiculous. Someone assuming #2 would be correct in saying "ok, that is dumb".

...

As a related bit, I once ran into a ladder-ending-in-a-cube trap. We spotted the cube before we got there. My bard proceeded to insult the cube to death.

Good times.

I think it would make sense that Vicious Mockery should require an int of over 2, like Synaptic Static. But then I couldn't use it on you, which would suck. What do you think?
/roll 3d4

 

[prabe]

It might be a fair trap, depending on whether the players have been given reason to expect ridiculous death traps. It might be a fun trap to encounter, for people who enjoy ridiculous death traps. It wouldn't be fair at the tables I'm DMing, because I've given the players no reason to anticipate that sort of crap.

 

[clearstream]

They're the same thing.

If you have a trap that wouldn't function, and shouldn't function, and you as the DM let it function, simply because some dude in 1980 had a terrible grasp on basic day-to-day physics and had forgotten Yellow Molds were insta-killed by fire, that would obviously be completely unfair on the players.

So having the trap function correctly is deeply unfair.

If you made it into a hilarious fail, which how it should actually work, then it wouldn't be unfair. Really if it's played honestly, it's going to fail one of two ways:

1) The players are suspicious as hell of the entire setup (as they should be) and easily discover the GC and kill it, and either move on or get it out and get at the treasure.

or

2) Fire gets involved in some way, and the trap basically self-destructs. There's just no plausible way the Yellow Mold doesn't catch on fire if the GC and rope are on fire. You'd be lucky if the Yellow Mold didn't go so deep into the GC that it detonated there anyway! Safely containing the spore.

So again it is unfair for the trap to WORK. This is an issue with a fair number of older traps in D&D. They were clearly written up by people with a tenuous grasp on physics and/or cause and effect, and not thought through at all.

Say that there is detectable magic surrounding the trap, which will accelerate the falling stone and splashing GC as needed? Is it fair in that case?

 

[Democratus]

I think this would be a fantastic trap if it was guarding something important.

For example, this is a dungeon competition hosted by an organization. At the bottom of the pit is the trophy.

 

[pemerton]

@Ruin Explorer

Ignoring air resistance, v^2 = u^2 + 2ax. If a = g, and u = 0, then we have v^2 = 20x. Let's say x = 3.5 m, then v^2 = 70 so v = 8-ish metres per second, or close to 30 kph.

That's not super-fast, but seems like it might cause a bit of Cube-squishing and splashing.

 

[Ruin Explorer]

Would it be correct to say that you can't picture something like this trap working?

It's not just "can't picture".

It can't function, as written. The designer clearly didn't understand the physics involved, and didn't remember that fire insta-kills Yellow Mold (unless it didn't in 1E).

Say that there is detectable magic surrounding the trap, which will accelerate the falling stone and splashing GC as needed? Is it fair in that case?

The lip still prevents the splash going horizontal. Simple physics. The splash will go vertical.

The Yellow Mold will always fail if the stone is going faster though, because the block will FULLY penetrate into the GC and the detonating of the Yellow Mold will occur INSIDE the GC - at best it would get people in the pit or clinging to the rope.

If fire is involved the Yellow Mold will always fail.

You would revise the trap to function. Remove the pit. Make the GC be in the middle of a room, around a pedestal with a treasure. Invisible and magically fed and unable to move. Remove the rope. Have the ceiling be a false ceiling with a shaft that's like 30' up. Have the falling block not be a block but say an 8x8 stone slab, the drop of which is triggered by the GC being significantly interfered with (again more magic to be detected - this thing would light up like a christmas tree on Detect Magic). This way the stone slab comes down on an unconstrained GC and will only splatter it horizontally, so everyone will be covered. The mold will fall a lot faster and on to a stone slab, and will function correctly rather than being IN A PIT AND ON FIRE lol.

 

[Crimson Longinus]

Does SP require such suspension of disbelief? Or only definite mechanical terms?

Would it be correct to say that you can't picture something like this trap working? Is that really an SP concern: so long as the DM is consistent and their players are in tune with them?

I mean if the players and the GM happen to have exactly similarly twisted understanding of reality, it might work. But that is unlikely. Skilled play requires deducing things about your environment and taking actions to overcome the dangers. If the environment is nonsense and actions do not have outcomes that they logically would, you cannot do that.

 

[Democratus]

@Ruin Explorer

Ignoring air resistance, v^2 = u^2 + 2ax. If a = g, and u = 0, then we have v^2 = 20x. Let's say x = 3.5 m, then v^2 = 70 so v = 8-ish metres per second, or close to 30 kph.

That's not super-fast, but seems like it might cause a bit of Cube-squishing and splashing.

Then there is the matter of the forced-damped harmonic oscilation after collision with the cube.

And what is the viscosity of the cube? It's structural integrity?

 

[Ruin Explorer]

@Ruin Explorer

Ignoring air resistance, v^2 = u^2 + 2ax. If a = g, and u = 0, then we have v^2 = 20x. Let's say x = 3.5 m, then v^2 = 70 so v = 8-ish metres per second, or close to 30 kph.

That's not super-fast, but seems like it might cause a bit of Cube-squishing and splashing.

That's an overestimate so something is wrong with your calculations (a human and a block won't be significantly different here).

http://www.greenharbor.com/fffolder/speedtime.pdf

Either way, it's still screwed due to the pit constraining it. It will splatter vertically. You know this because you live in a world where physics applies. The ceiling would be covered in GC, but not the area around it. Maybe the 5' squares exactly next to it would get some. But if you have the lip you described it's going to be even more vertical than that.

On top of that you still have a slow deceleration into goo.

Goo which is probably ON FIRE.

Fire which kills Yellow Mold instantly (no damage, no hit, just fire kills it).

Even if it isn't on fire, the spore-explosion is constrained because the block is 10' down and surrounded by goo and possibly has goo on top of it even.

Literally the best-case scenario for this pit is someone jumps in without the slightest check, finds the invisible GC, and for some reason the PCs try to set it on fire with him in it (those bastards!), at which point the block falls, possibly killing him, and possibly exposing him to spores in the fraction of second before the Yellow Mold dies in a fire. I've explained upthread how to make a trap based on the same basic principles but which would actually work.