Making a Knock-proof Lock

[RickAllison]

As in the title, this is a brainstorming thread for how to make a lock that is safe against those who would bypass the defenses using Knock, the easy way out, as well as to be generally difficult to pick.

This was inspired by my Minotaur wizard. Each of my previous characters has been great at breaking into places, but I want this to be someone great at keeping them out. He has tinker's tools proficiency, Fabricate, and Arcane Lock, but now he needs a design. Here is what I have so far:

The lock is operated by several gears all manually rotated by the key, and it features a second mechanism that will engage other locks if it is not depressed while unlocking the gears.

The key of this design has two parts. It has a head that looks like a standard skeleton key; this is the secondary fail safe mechanism and is held in place during the operation of the main key by a secondary haft under the main haft. The main haft looks like a normal skeleton key, but inserting and rotating the key in the lock as normal holds a shade in the main mechanism barrel that allows for the gear teeth to mesh with the gears in the lock. The main haft is then rotated to engage the gears.

Would this work?

[pwykersotz]

As in the title, this is a brainstorming thread for how to make a lock that is safe against those who would bypass the defenses using Knock, the easy way out, as well as to be generally difficult to pick.

This was inspired by my Minotaur wizard. Each of my previous characters has been great at breaking into places, but I want this to be someone great at keeping them out. He has tinker's tools proficiency, Fabricate, and Arcane Lock, but now he needs a design. Here is what I have so far:

The lock is operated by several gears all manually rotated by the key, and it features a second mechanism that will engage other locks if it is not depressed while unlocking the gears.

The key of this design has two parts. It has a head that looks like a standard skeleton key; this is the secondary fail safe mechanism and is held in place during the operation of the main key by a secondary haft under the main haft. The main haft looks like a normal skeleton key, but inserting and rotating the key in the lock as normal holds a shade in the main mechanism barrel that allows for the gear teeth to mesh with the gears in the lock. The main haft is then rotated to engage the gears.

Would this work?

Nice, so the only way to open it is NOT to open the second lock.

Other than handwaving "This lock cannot be bypassed by Knock", I think you're on the right track. But Knock states that only one lock is unlocked anyway, so an analysis might allow a Wizard to target the lock that needs to turn anyway. I think dual locks which must be unlocked at the same time is a good idea, and an auto-re-locking mechanism if only one is opened.

That said, it also says that it only works on mundane locks. Yours is custom and fancy-pants. Therefore, Knock might not work anyway. :smallsmile:

[jas61292]

Well, my thoughts on making a knock proof lock have always been either locks that have to be opened simultaneously or else they relock, as pwykersotz suggested, or to design a mechanism with multiple locks such that they need to be unlocked in the proper order, or else unlocking one will re-lock the others. While the latter doesn't technically block knock, it could require many castings of it, potentially keeping a mage out for a long time, and it has the advantage of only needing one actual key to get through.

That said, I miss the old 3.5 way of foiling knock: big doors. It was so dumb, but I loved it so much.

[RickAllison]

Nice, so the only way to open it is NOT to open the second lock.

Other than handwaving "This lock cannot be bypassed by Knock", I think you're on the right track. But Knock states that only one lock is unlocked anyway, so an analysis might allow a Wizard to target the lock that needs to turn anyway. I think dual locks which must be unlocked at the same time is a good idea, and an auto-re-locking mechanism if only one is opened.

That said, it also says that it only works on mundane locks. Yours is custom and fancy-pants. Therefore, Knock might not work anyway. :smallsmile:

Thanks. I sketched out the first iteration in my Spanish Morphology and Syntax class. Originally, it was using a spiral strip of metal as the lock mechanism. Basically, it relied on the physical presence of the fail-safe or else the motion of the mechanism would not be arrested and so would engage the secondary locks and an alarm system.

These are certainly not compact locks. This is more like a lock for safes and kings than the average door...

[JumboWheat01]

Trap locks are good. If not disabled and picked by someone with the proper skill and tools, BOOM! There goes someone's face and all the loot.

[SharkForce]

knock works on one lock. so you just need more than one lock that is designed to relock itself after an appropriate amount of time.

alternately, you can exploit the other requirements, like making the object to be unlocked difficult to see (if you make a fake door that looks real and a real door that looks fake, odds are they'll cast knock on an invalid target. alternately, you could have it in a very dark place). you could also place the object to be unlocked out of range (perhaps by having some sort of construct that you simply hand a key to, have it walk through a tunnel, use the key, and return it somehow).

you could have a lock that engages any time a loud noise is heard.

you could also just have the door guarded. or appear to be guarded. if there are two large stone statues next to the door with a warning against using magic on the door, plus a properly applied nystul's aura, most people will assume the door won't react well to a knock spell :P

you could have the door guarded for real. a few heavily armed guards with weapons is a fairly effective deterrent against most people.

finally, while it's a bit unclear whether this is completely within the rules, I see no reason a glyph of warding loaded without counterspell could not be set up to counterspell things cast at the door in terms of plausibility. afb, so I'm not sure the rules technically allow for that.

[RickAllison]

Trap locks are good. If not disabled and picked by someone with the proper skill and tools, BOOM! There goes someone's face and all the loot.

One of my back-up systems in case this didn't fly was routing the opening to a latch that would open and trigger a Glyph of Warding if the fail-safe wasn't used. I like Explosive Runes...

(Though I would probably instead use a spell. I am an Artificer, so making one with a 9th level spell is actually possible...

[JumboWheat01]

One of my back-up systems in case this didn't fly was routing the opening to a latch that would open and trigger a Glyph of Warding if the fail-safe wasn't used. I like Explosive Runes...

(Though I would probably instead use a spell. I am an Artificer, so making one with a 9th level spell is actually possible...

And suddenly that chest you wanted to open up is now a dragon. It's not very pleased at an attempt to make it give up shiny treasure.

Does that count as a surprise round?

[krugaan]

One of my back-up systems in case this didn't fly was routing the opening to a latch that would open and trigger a Glyph of Warding if the fail-safe wasn't used. I like Explosive Runes...

(Though I would probably instead use a spell. I am an Artificer, so making one with a 9th level spell is actually possible...

or maybe something like "if this chest is unlocked by any other method than this key (trigger), it teleports / planeshifts / demiplane whatever out of reach."

Non-lethal and doesn't, you know, ruin everything inside.

Note: do not use this on doors.

[Shining Wrath]

I solved this problem by, as has been suggested, putting multiple locks on a door that reset in a round.

You can also put the door in a place where to see it the wizard must be close to it. That way if Silence is used to avoid the loud noise of the spell, the wizard must have Subtle Spell metamagic - AFB, don't remember if Sorcerer spell list includes Knock. Noisy knocking combined with guards is not desirable.

[krugaan]

I solved this problem by, as has been suggested, putting multiple locks on a door that reset in a round.

You can also put the door in a place where to see it the wizard must be close to it. That way if Silence is used to avoid the loud noise of the spell, the wizard must have Subtle Spell metamagic - AFB, don't remember if Sorcerer spell list includes Knock. Noisy knocking combined with guards is not desirable.

Whats sort of funny is that the only component for knock is verbal. So if you can subtle spell knock you can pop locks and make a loud noise while doing ... nothing.

[smcmike]

Multiple resetting locks is nice and also simple (not that I have the mechanical wherewithal to build a resetting lock). It only loses points for presentation - one keyhole would be more elegant - and the possibility of double wizards.

I also like the idea of a failsafe triggered by the loud noise, and the idea of a short hallway to prevent strategic silence placement.

How about a failsafe that triggers on Silence? A metronome would work if anyone can come up with an appropriate mechanical audio receiver to trigger on the lack of noise. Alternatively, a metronome and a guard station connected by some hidden acoustical piping...

[krugaan]

one fairly viable way to have resetting locks is to have them all reset if the lid is opened (without the locks all being disengaged).

Or have them all lock if you don't open the lid while pushing a secret catch or something.

[Professor Gnoll]

Or make a lock out of a tiny, bound imp that sits inside a box on the door and will only release the catch when presented with the right key. Can't cast Knock on that.

[krugaan]

Or make a lock out of a tiny, bound imp that sits inside a box on the door and will only release the catch when presented with the right key. Can't cast Knock on that.

Lol, the Half-lock ... a halfing that sits on the chest lid.

[Professor Gnoll]

Lol, the Half-lock ... a halfing that sits on the chest lid.
A halfling clad in full magical ultra-plate with an AC of one million, an anti-magic field centred on it, and a burning zeal to only open the chest for those that have the key.

[R.Shackleford]

Lol, the Half-lock ... a halfing that sits on the chest lid.

Half-Elf Warlock?

A Warlock that has a fey pact with a very powerful Half-Elf?

[RickAllison]

A halfling clad in full magical ultra-plate with an AC of one million, an anti-magic field centred on it, and a burning zeal to only open the chest for those that have the key.

I suppose this begs the question, can you program a Geas into a Glyph of Warding? I like the idea of every person who failed to pick the lock having to remain quiet and protect the chamber. It would be a fitting punishment.

[Professor Gnoll]

I suppose this begs the question, can you program a Geas into a Glyph of Warding? I like the idea of every person who failed to pick the lock having to remain quiet and protect the chamber. It would be a fitting punishment.
Unfortunately not, as Glyph of Warding only allows for 3rd-level or lower spells to be programmed into it. But I'm sure you could figure out a way to do it.

[RickAllison]

Unfortunately not, as Glyph of Warding only allows for 3rd-level or lower spells to be programmed into it. But I'm sure you could figure out a way to do it.

You can if you cast it at a higher level!

[Professor Gnoll]

You can if you cast it at a higher level!
Damn, I totally missed that. Then the Geas lock is a reality!

[krugaan]

or have a familiar inside the chest who readies an action to relock the chest every round, lol.

[BW022]

I tend to find the best knock proof locks are false doorways which can't be opened (which have lots of locks, spells, traps, and affects on them) and then a 'hide in plain sight' type concealed door.

For example, the PCs come to a double doorway make of a iron, with three bars, two sets if chains, a silver disk symbols, and radiating all sorts of magic. There is also a large brazier of continue flame causing the silver disks to reflect a bright light. The has various traps on it. The doors appear to open outward. However, they don't actually open -- they are one piece of metal which look like a seam between them and face solid stone behind them. There is a secret door in the ceiling with no lock and you merely push up with 200 lbs of force. You can use the bars and chains on the doorway to climb up.

Most parties will look at the iron doors and immediately look for traps, try disarming them, detect magic, try various knock spells, push, pull, blast, try digging around it, etc. The bright brazier light reflecting off the disks makes searching for secret doors difficult.

[R.Shackleford]

I don't mind that knock can open locks. It has its downsides.

It's noisy as all hell. Typically if you are worried about a lock then it is best to stay quiet.

Hell, I've seen more Urchin Wizards than Wizards with knock.

As a DM I get to choose when locks exist, if the lock is even locked at all, and what purpose the lock has. I don't use locks for the purpose of draining resources, that just gets annoying after a while.

However if a player had the spell knock memorized and ready to be cast... I would incorporate it into the battle somehow. Actually I would do this if there was a thief in the game or people who had the urchin background and liked to unlock things...

Perhaps big monster has a series of locked collars in its neck, arms, legs, and perhaps tail. These are giving the enemy co trip over the monster. For each lock that is unlocked, the enemy can't control the beast as well as before.

There are two options, climb onto a bigger creature and unlock them or cast knock.

Another good use for knock is that I typically have chandeliers or other stuff handing around. Dropping them in an enemy or three will kill them or cause the enemy to drop what they are holding and catch the chandelier. This leaves the enemy open to attacks... Though I had a Paladin and Ogre play catch with a large metal chandelier once... They both used it as a ranged improvised weapon...

[Democratus]

How do you drop a chandelier with a Knock spell?

[R.Shackleford]

How do you drop a chandelier with a Knock spell?

Chandelier has a lock keeping it in place. If the chandelier is ever broken or just not up to style then the owner needs a way to remove it from the ceiling and fix/replace it.

Its safer to lock it to a set of three chains hanging from the ceiling than not. Besides keeping up with the BBEG-OSHA guidlines are very important... You don't want some PC taking you to court!

Knock works on mancles and padlocks, having three chains run down and connect to a chandelier via a lock is no problem.

[OldTrees1]

The door is unlocked, but the handle will not open/shut the door unless the handle is locked to the bolt. So Knock could be used to disable the door, but skill would be required to enable the door.

Oh, and the classic: Unlocking the lock on the stone door releases a heavy weight to rest on the door. Now it is unlocked but stuck. Replace weight with metal rods passing through the door into the ground at higher levels.

[Giant2005]

Don't use a lock.
Have your door just be a stone slab with a series of inaccessible block and tackles above it to lift it when necessary. Have those block and tackles controlled by a cog system. Have on of those cogs be as elaborate as a key as to not be easily reproduced, and that that cog with you, using it like a key.

[OldTrees1]

Don't use a lock.
Have your door just be a stone slab with a series of inaccessible block and tackles above it to lift it when necessary. Have those block and tackles controlled by a cog system. Have on of those cogs be as elaborate as a key as to not be easily reproduced, and that that cog with you, using it like a key.

Isn't that a lock? It is a big and heavy lock but it fits the key + locking mechanism concept of a lock. However both your idea of not using a lock and your idea of a pulley system are good ideas.

[Demonslayer666]

It's more like a spark plug than a key. A necessary part to make the mechanism work/move.

As with everything, this is going to weigh heavily on the DM's ruling and what they think Knock can do. If two lock are connected in a way that one relocks the other, it might be considered one lock. That's the first thing that came to my mind.

[Temperjoke]

Modern safes have a pane of glass in them that, if broken, prevents the safe from being unlocked by spring locking multiple pegs into place that have to individually be cut in order to open. Or something like that. So if your door has that mechanism internally, it could be magic sensitive or triggered by the aforementioned 2nd lock if not unlocked properly.

[TentacleSurpris]

Roll a giant heavy boulder behind the door to keep it closed.

[JumboWheat01]

Roll a giant heavy boulder behind the door to keep it closed.

Ah, the good ol' prop a chair to the door trick. This is why I always suggest disintegrate. Who needs to worry about a locked whatever if the locked whatever no longer exists.

[Segev]

You really do need an n-locks approach. And arguably, you cannot have them interconnected in any way that has one activate, de-activate, or even detect the others' state(s), because if you do, they might qualify as "one" lock.

The OP's design, while nifty and clever, sadly easily qualifies as just one lock, albeit a fancy one. Knock unlocks a lock. If you have a key or combination that can unlock it, knock will do it. Even if it's a multi-key lock, if it's one lock that functions together as one piece when activated "properly," knock should unlock it. It is a limited-use, but powerful-in-its-purview, spell.

Now, a lock which automatically re-locks? That would be nasty to a knock spell. I don't think anything in the spell says that it keeps the lock open for any length of time. So imagine a lock which you had to hold the key in place to keep unlocked. Let go, and, like a door knob in most modern doors, the lock mechanism's internal springs push the key and the latch back into place immediately. So the knock spell would unlock it!...and then it would re-lock itself immediately. You'd have to basically time your opening to be as fast as how you'd have to do it if you were trying to open a door whose knob you let go of just before you pulled/pushed.

Or you could try shoving a card or placard into the latch, if you can reach it, to block it from falling back into place.

[OldTrees1]

Ah, the good ol' prop a chair to the door trick. This is why I always suggest disintegrate. Who needs to worry about a locked whatever if the locked whatever no longer exists.

Careful, I can think of several dwarven traps that would be quite devastating if you disintegrated a boulder barred door(the boulder for one). Best to cast from behind some shelter.

[Temperjoke]

Careful, I can think of several dwarven traps that would be quite devastating if you disintegrated a boulder barred door(the boulder for one). Best to cast from behind some shelter.

The other downside is, if you need to leave the room, how do you lock the door if your lock is a large boulder on the other side of the door?

[R.Shackleford]

The other downside is, if you need to leave the room, how do you lock the door if your lock is a large boulder on the other side of the door?
Normal boulder would be fabricate, worked stone would be fabricate normal boulder + some stone work. :p

[JumboWheat01]

The other downside is, if you need to leave the room, how do you lock the door if your lock is a large boulder on the other side of the door?

Just bypass the door altogether with a good ol' Passwall! The wall will return to normal once the spell time is up.

[Temperjoke]

Just bypass the door altogether with a good ol' Passwall! The wall will return to normal once the spell time is up.

But then why bother with a door at all? They can't use knock on a lock, if there is no door to be unlocked.

[JumboWheat01]

Well the minions need to be able to get around. And what's the point of being a good ol' evil overlord with lockable things if you don't have any minions?

[Temperjoke]

The levels that the minions are allowed on don't have lockable doors.

1. I don't trust them to keep the keys safe from enemies.
2. I don't want them trying to hide if I'm in a bad mood or on a tantrum rampage.

[RickAllison]

The levels that the minions are allowed on don't have lockable doors.

1. I don't trust them to keep the keys safe from enemies.
2. I don't want them trying to hide if I'm in a bad mood or on a tantrum rampage.

Considering my wizard is one ASI from being a 20 Strength grappler whose specialty is Potions of Growth as an Artificer, the second reason would be very apt. No minion wants to disappoint a 15'4", 3,520 lb minotaur whose favorite method of attack is impaling his enemies with flaming horns...

(7'8", 440 lb minotaur with growth for doubled height and 8X weight. Likes grabbing two foes and Green-Flame Blading with his horns)

EDIT: Just ran some numbers. Between the Horseshoes of Speed my DM decided my minotaur could use (so base speed of 60'), Expeditious Retreat giving bonus action Dash, the Enlarge effect (also affecting 80+ pounds of equipment), and a Haste effect (he was buffed out at the time), getting run into by my minotaur this past Sunday would be roughly equivalent to getting hit by a minivan at 41 MPH. You know, except for giant horns rather than a bumper...

[krugaan]

Well the minions need to be able to get around. And what's the point of being a good ol' evil overlord with lockable things if you don't have any minions?

Just so long as the official Evil Overlord Minion Helmet (tm) has no face obscuring faceplate!

[JackPhoenix]

The lock isn't Knock-proof.

But there is another door with its own lock just behind the first. Possibly with the trollface painted/carved on.

Add as many doors as you want.

[Knaight]

Security through obscurity could work here. Knock targets the lock, so if the mechanism to open the door isn't at the location of the door but is instead hidden somewhere, then knock is useless until found.

There's also the brute force method where knock can't target an actual wall, so if you have a wall, a wall cutting mechanism, and a wall repair mechanism you could use that as a door of some sort. Some sort of self growing crystal wall with explosive properties if properly triggered could work.

[soldersbushwack]

The range on Knock is 60ft. Have a complicated apparatus that takes a key and reproduces the shape of it on a 70ft long stick and then have some kinds of levers that let you control the stick and insert the shape into the actual lock.

[R.Shackleford]

I really don't like a lot of these responses of "screw knock RAWR" that sets up the "DM versus Player" dynamic.

Of you don't like the spell just ban it so the caster can get some use our of that spell known/prepared/slot.

[RickAllison]

I really don't like a lot of these responses of "screw knock RAWR" that sets up the "DM versus Player" dynamic.

Of you don't like the spell just ban it so the caster can get some use our of that spell known/prepared/slot.

Oh you misunderstand, I'm a player in the campaign! I think it makes perfect sense that a wizard who knows that Knock and Passwall trivialize defenses would have incentive to stop those methods. I'm still working on Passwall...

[Temperjoke]

I really don't like a lot of these responses of "screw knock RAWR" that sets up the "DM versus Player" dynamic.

Of you don't like the spell just ban it so the caster can get some use our of that spell known/prepared/slot.

Well, for me, it's not so much being adversarial as opposed to wanting to create a puzzling challenge for the PCs. I mean, there are going to be lots of times that just letting them use Knock is going to be perfectly fine, or even making sense in the context of things. On the other hand, there are also going to be times where something more complex is required. I mean, the same sort of locks that Knock could open, could potentially be picked by a rogue or criminal background, so having a rare lock that requires a little more thought isn't a bad idea.


Oh you misunderstand, I'm a player in the campaign! I think it makes perfect sense that a wizard who knows that Knock and Passwall trivialize defenses would have incentive to stop those methods. I'm still working on Passwall...

Just make the walls out of metal for that particular room; for a fancy touch make it out of something rare like mythril!

[Professor Gnoll]

I think we go back to the Imp idea. Construct the entire room, door and lock out of thousands of tightly-packed imps with magical protection. When presented with the correct key, they will rearrange to form an opening for you to pass through.

[SharkForce]

Security through obscurity could work here. Knock targets the lock, so if the mechanism to open the door isn't at the location of the door but is instead hidden somewhere, then knock is useless until found.

There's also the brute force method where knock can't target an actual wall, so if you have a wall, a wall cutting mechanism, and a wall repair mechanism you could use that as a door of some sort. Some sort of self growing crystal wall with explosive properties if properly triggered could work.

in 5e, knock actually targets the object you want to open.

[R.Shackleford]

in 5e, knock actually targets the object you want to open.

What else is a wall other than a lock which the key to is a raging barbarian?

Knock totally target a wall.

[Knaight]

I really don't like a lot of these responses of "screw knock RAWR" that sets up the "DM versus Player" dynamic.

Of you don't like the spell just ban it so the caster can get some use our of that spell known/prepared/slot.

The vast majority of doors will still be viable, and one tactic not working because the NPCs thought to counter it is hardly a "DM versus Player" dynamic. This is particularly true given that the OP is a player, and currently trying to make defenses that can withstand expected highly available tactics.