The grandaddy of gaming supplements of this nature has to be Grimtooth's Traps, produced by Flying Buffalo back in 1981. These grimoirs contained some of the most creative and deadly traps Ive ever seen in one place ( with exception of the infamous Tomb of Horrors). The artwork in these books is awesomely twisted and convey a real sense of impending doom and just reading them used to make my skin crawl.
Some of the traps are silly, some are cleaver, some are preposterous, but most are incredibly horrific. The books do a good job of not only providing clearly detailed drawings of how each trap works, but also along with the description of each trap, they rate each trap with a number of skulls to represent how deadly the trap is, from 1-6. The original Grimtooth's traps didn't give any game mechanics information, making these supplements compatible for most any fantasy gaming system. All you had to do was adapt the trap to your game and use the skull rating system as a means to gauge how deadly the trap should be.
I think these books are a must for any dungeon designer and even if you don't use them, they are a good read just the same.
Presented here are some of my own devious traps I designed and have used in the past for some of my former players and their poor characters. My artwork isn't nearly as good as the artwork in Grimtooth's, but I think you get the idea how each trap works.
Id be interested in hearing if other people have these books and have used them. Also, what cool and cleaver tricks and traps have you designed for your adventurers?
1) Pandora's Box or The Lifetrapping Chest Trap- I originally designed this trap as a final encounter for my group to over come in order to reach their quest item. The trap consists of an iron chest that is permanently attached ( bolted?) to the floor. The chest is locked with a simple lock to deflect any suspicion. Inside the chest, on the bottom is the quest item ( or treasure if you will). Attached permanently inside the chest mid way facing up is a Mirror of Life Trapping. The Chest is hinged with a spring hinge. When the chest lid is opened, anyone viewing the contents of the chest must immediately save vs magic ( AD&D DMG pg 150) or disappear ( in a flash of light) into one of the mirrors cells. The lid will then automatically close. Those viewing the encounter will only see the person open the chest and look in and disappear. If the person makes their save, will see a flash of light and be stunned for a brief moment while the lid closes again automatically. If, through cautious exploration, the mirror is detected, then the mirror must be smashed in order to access the contents underneath. Now while this will also release any members of the party that got trapped in the mirror, it will also release any other creatures previously trapped in the mirror as well. I suggest an angry Elemental, a nasty Type III demon and a hungry vampire. Oh, and lets not forget a lawful good Lammasu- one must always have hope <g>.
2) The Pillars Have Eyes Trap- This trap is well placed as the entrance to a wizards abode or other such individual that wishes to deter would be interlopers. A short flight of steps leads up to the a door in an arched opening. Two simple stone columns adorn either side of the door. If detected, the columns and door detect as magic. Obviously a trap... but what kind? Well, once the trap is sprung ( by attempting to open the door without the password), the two pillars, which are polymorphed charmed Ropers (Monster Manual pg 83), revert back to their normal form and attack ( or if you prefer, have two Storopers instead MMII pg 115).
3) The Vaccuum Trap Or What Happens When You Put A Portable Hole into A Bag of Holding Again?-
This trap can be placed in a chest or behind a false door. The trap is simple. A thin line attached to the inside of the lid of the chest ( or inside of the false door) dangles over an opened Bag of Holding. Attached to the end of this line is a folded up Portable Hole. The line is set up in such a way that if the chest lid is opened ( or the door opened), the line will break and drop the folded up Portable Hole into the Bag of Holding. This immediately creates a dimensional rift in the Astral Plane and sucks everything within 10ft of the chest/door into it, the Bag of Holding and Portable Hole being destroyed in the process ( DMG pg 152). Now a cleaver adventurer who inspects this trap, may find a way to diffuse it and thereby gain a Portable Hole and a Bag of Holding ( and what ever contents the bag may have).
4) Cute and Cuddly and Metal Hungry Trap- This is a simple trap that I designed from a similar use used in module A3 of the Slavers Series of modules. Great for a wizard to keep in his lair or tower. Just fill a room with a few of the cutest cuddly creatures you like ( kittys, bunnies, chinchillas, whatever) and let the adventurers come upon them ( or have them roaming about the lair). The only hitch is that some of these cute little creatures area really small rust monsters disguised by permanent illusion. Unfortunately, this wont become apparent until after the kitties lovingly swarm about the fighters legs purring and turning his armor and weapons into rust. But who's going to kill a poor cute little defensless chinchilla?
5) The Cuisinart Trap- This nasty trap is placed in a hallway. The party comes to a pit in the hallway that takes up the entire space. The pit may be very deep with spikes or perhaps bottomless. Spinning over the pit, on a rotating axle are three very large circular steel blades each approximately 3 ft apart. They are so large they almost touch the ceiling and the edges of the pit and extend a few feet into the depth of the pit itself. The obvious means of passing through this trap, would be to jump or somehow pass between the spinning circular blades. The only problem is, these blades aren't real, they are illusions. The real blades are invisible and are spinning to the right and left of the center illusionary blade. If the group does some cleaver investigation ( 10 ft pole anyone) and determines the existence of the illusion and the invisible blades, this trap can be overcome, otherwise, their mincemeat. I always place a hungry monster at the bottom of the pit, awaiting their sliced and diced morsel to drop to them
6) Who Pulled The Plug Trap- This is a rather simple water trap I designed. The adventurers come to an empty room. As they move in to search, a pressure plate is activated that releases a stone door that drops down and seals the room. If the group searches the room, they find in the center of the ceiling 20ft over head is a metal ring attached to the ceiling. This metal ring is actually the stopper to a Decanter of Endless Water that is inserted into the ceiling upside down. Once the stopper is pulled out, the decanter releases a geyser of water into the room, knocking down anyone underneath (DMG pg 142, I bypass the command word to activate this ability, or have a magic mouth take care of that if your that particular). The room begins to fill up with water and perhaps a concealed door opens up and releases a nasty monster to keep the adventurers busy while the room slowly fills ( undead or an amphibious creature). Now, there is a way to escape, all the group has to do is find the damn stopper which has the command word written on the inside of it and use it to cease the flow of water. Shoving the stopper back into the decanter which will depress a release plate set at the base of the decanter that will cause the stone door to retract. Now if the adventurers have a Flesh to Stone Spell, or want to devise a way to chip into the stone ceiling and remove the decanter ( assuming they figure out that's what it is) well then they got themselves a nice prize for their efforts.