Deflect llghtning trap?

[Edhelras]

I'm designing a wizard's tower with a narrow entrance, in the door is placed a lightning bolt trap (CR4).
The party (lvl 4) need to go through that door in order to enter the tower. However, approaching the door, the alarm will go off and they get hammered with lightning bolts every round. So it's meant to be a deadly trap to keep unwanted visitors out.

I want to place things that creative players can use to counter this lightning bolt trap when trying to enter the tower. What would help them negating the trap?
Would a mirror deflect the lightning bolt, or would it shatter?
What about a sheet of steel?
Perhaps metal plating from the roofs?

The lightning bolt spell says:
"The lightning bolt sets fire to combustibles and damages objects in its path. It can melt metals with a low melting point, such as lead, gold, copper, silver, or bronze. If the damage caused to an interposing barrier shatters or breaks through it, the bolt may continue beyond the barrier if the spell’s range permits; otherwise, it stops at the barrier just as any other spell effect does."

I was thinking perhaps an angled mirror might deflect the bolt rather than break from the impact, but no?

Any other ideas how to defeat this trap (with lvl 4 party resources) ?

[Rebel7284]

I mean, usually the specifics are skipped over and folks use a skill check instead. That's what disable device is for.

[Edhelras]

I mean, usually the specifics are skipped over and folks use a skill check instead. That's what disable device is for.

Yeah, well, the idea was this gauntlet with a narrow corridor so you cannot approach the trap to disable it. The DC is also quite high for a lvl 4 rogue (28).

So I was imagining they would need to do something to get close up to the trap in order to disarm it.

[InvisibleBison]

I don't think you need to prep anything specific. If your players are creative, they'll come up with ideas on their own. If they aren't, it won't occur to them to use anything you've placed in the area against the trap.

Also, I think you're misreading how the trap works. A proximity trigger is tripped by a creature approaching within a specific distance of the trap, not by a creature being within that distance. So unless the PCs repeatedly exit and re-enter the guarded area they'll only be blasted once.

[Sire Pepe]

Yeah, well, the idea was this gauntlet with a narrow corridor so you cannot approach the trap to disable it. The DC is also quite high for a lvl 4 rogue (28).

So I was imagining they would need to do something to get close up to the trap in order to disarm it.

That sounds like a pretty difficult trap for a low-level party!

You could design a flaw in the defense mechanism, here are a few ideas:
- The alarm is triggered by a pressure plate, and may be circumvented by flying, or moving on the walls or ceiling‧
- The trap can be disarmed from afar, by using projectiles or some form of telekinesis.
- Invisible creatures do not trigger the alarm.
- Make it possible for some creatures to avoid the trap. For example, a tiny familiar could crawl under the shooting bolts, or a summoned creature could be immune to the type of damage dealt by the trap (although I don't think there are any summonable creatures that are immune to lightning at level 4...Lemures are resistant to many other forms of energy, however)

Otherwise, you could provide the party with an item that would protect them from the lightning bolts. They might have to find said item in a hidden compartment, buy it from an NPC, or something. It doesn't have to be super easy.
- A scroll of protection against energy might do the trick.
- You could design a homebrewed lightning rod. That could lead to enigmatic or funny situations. I feel like your mirror idea goes in that direction, but I see no reason why an ordinary mirror would stop a lightning bolt...

The party could always try to buff up their rogue to give them a chance to reach the trap's mechanism with spells and whatnot, but I would personally feel pretty frustrated if I had to start an adventure looking like roasted chicken...

Finally, you could change the spell for a less powerful one. Even if the trap triggered regular arrows, magic missiles, acid arrows, or scorching rays, it would be a pretty strong deterrent for players to just charge headlong into that door, because their sheer number would cause the party enormous damage (potentially even death) and deplete their ressources early in the adventure. However, it would provide them with a chance to circumvent the attacks with the right spells.

I hope this helps :)

[Khedrac]

The rules for spells (especially for lightning bolt) and how they interact with barriers inside the spell area have varied a lot over the various editions of D&D, so looking specifically at 3rd Ed:

Q1: What happens if a damage-causing AoE spell reaches a barrier to line of effect before the end of the area?
A1: The spell stops and the spell's damage is applied to the barrier. If the damage breaches (destroys) the barrier the spell's area is calculated as it the barrier wasn't there (i.e. as normal).

Q2: So will a lightning bolt or other line spell reflect off an angled barrier?
A2: Not by the rules, if you want it to set a house rule, but make sure remember it for the future and expect players to start bouncing spells round corners.

Q3: So it's a lightning bolt, that means the PCs can earth (ground) the spell with a conductive metal barrier?
A3: No, this is D&D, magical electrical attacks do not conduct like real-world electricity, all the 3rd party modules that use this trick are wrong.

Q4: This means I am going to have to understand the damage to object and hardness rules doesn't it?
A4: Not totally, but an general understanding is needed. You only need to worry about electricity so start by dividing the spell's damage by 2 (the blocking object doesn't get a save, but electricity does half damage to objects) before you subtract hardness. The objects have a distinct number of hit points per inch of thickness so it is simple maths. See here (http://dndsrd.net/carryingAndExploration.html) (bottom of page).

If the players say a carried blocking object should get their reflex save point out that if they want to jerk it out of the way of the trap so the spell gets to carry on to hit them, they are welcome to try...

Incidentally, the way tras in 3.5 are supposed to work is that if the trap can act on the PC then the PC can attempt the disarm (so it can be disarmed at whatever range it can be triggered). This is completely different to older versions of D&D and doesn't make much sense logically, but is much fairer to players. And as for the "making sense" part, consider how Haley disarms this (https://www.giantitp.com/comics/oots1220.html) trap - rogues' ability to disarm magical traps is as much about knowing how to set up interference patterns in stationary magical effects as it is physically interacting with origin of the trap. That's why Spell Turrets were invented.

Edit: despite what I have said, remember rule 0 - most important is that all players (including the DM) have fun, rules are secondary to this.

[InvisibleBison]

Incidentally, the way tras in 3.5 are supposed to work is that if the trap can act on the PC then the PC can attempt the disarm (so it can be disarmed at whatever range it can be triggered).

Really? I've never heard of this before. Where is this rule found?

[Edhelras]

Also, I think you're misreading how the trap works. A proximity trigger is tripped by a creature approaching within a specific distance of the trap, not by a creature being within that distance. So unless the PCs repeatedly exit and re-enter the guarded area they'll only be blasted once.

Ah, thanks, yeah I misunderstood that. I thought it would be firing continually.

However, if the party approaches the trap one at a time, or say sends the rogue up ahead, I guess the trap will get two shots, right?


EDIT: Thanks Sire Pepe and Khedrac for great input, lots of good information and nice ideas!
The point here was to create a kind of forbidding trap, that would require some amount of ingenuity, teamwork and exploration in order to overcome.

BTW i kind of miss the lightning bolts from Baldur's Gate (or rather, I don't miss'em, I hated them...) that kept on going back and forth until the line was expended, hitting the target several times until they were charred...

[Bohandas]

What about a sheet of steel?
Perhaps metal plating from the roofs?

...

Any other ideas how to defeat this trap (with lvl 4 party resources) ?

Some kind of faraday cage, perhaps made from the metal sourced from the places you mention

[Edhelras]

Some kind of faraday cage, perhaps made from the metal sourced from the places you mention

Right!

I was thinking of something akin to this: https://www.giantitp.com/comics/oots0808.html

[sleepyphoenixx]

If it's a lightning bolt as the spell you can simply block it by using a (possibly improvised, though that's up to the DM) tower shield in total cover mode.
As long as it doesn't destroy the shield whoever hides behind it will be fine, though depending on the CL a non-magical tower shield will likely break after 2-3 hits.

[Fouredged Sword]

Anything that provides total cover and can survive the damage the tower dishes out would render the effect of the trap moot. A fighter could, if he wanted to, hide behind a tower shield and advance towards the trap. He would have total cover from the direction of the trap, meaning that the trap cannot target him.

[ciopo]

is this trap already inside the tower, or in the "approach" to the tower?

if it's outside, I would change lightning bolt for call lightning, that way you can have it do it's damage in subsequent rounds, but it's generally less deadly than a repeated lightning bolt, because you do 3d6 5-10 times but on single targets, rather than 5-10d6 damage once but to potentially more than one target, with the potential "creative" solutions of "I go prone so I'm not the tallest standing member" or "I raise my sword to the sky so I absorb the next bolt instead of (other player)"

[Edhelras]

is this trap already inside the tower, or in the "approach" to the tower?

if it's outside, I would change lightning bolt for call lightning, that way you can have it do it's damage in subsequent rounds, but it's generally less deadly than a repeated lightning bolt, because you do 3d6 5-10 times but on single targets, rather than 5-10d6 damage once but to potentially more than one target, with the potential "creative" solutions of "I go prone so I'm not the tallest standing member" or "I raise my sword to the sky so I absorb the next bolt instead of (other player)"

Thanks, great idea!

The trap was meant to be situated in the approach to the tower, in a kind of gauntlet or narrow corridor leading up to the front door. In the meantime, I've thought about some other solutions, based on advice here. But I still think it's nice to discuss non-rogue, non-Disable Device ways to protect against lightning traps.