Mastering at Game Master: Traps Episode.031

Shoving the door with your shoulder, it wedges open just enough for your skinny companion to slip through the crack.  He forgets to be quiet and whistles in aw, which echoes off the walls of the large room inside.  Someone has gone to the trouble of nailing furniture to the walls and ceiling, creating a strange sensation of being almost upside down.  When you enter the room, the combined weight of the two of you causes the floor to drop suddenly down.  It appears the entire room is shaped like a sphere with no 90 degree edges anywhere.  The ball-shaped room quietly rotates and swings gently up and down to compensate for the sudden added weight before settling back down, albeit slightly below level.  You wonder what the purpose of this room was as you try to make your way across, readjusting your step as the unstable floor continues to rock from your motion.  Your foot almost trips over a wire, but it snaps to your strength.  Suddenly the pivoting room begins to churn and rotate faster, despite your weight.  The speed intensifies rapidly as you feel the force slowly push you down to the floor.  Dizzily spinning, you realize you have but a minute to figure out a way out of this trap before the force will render you unconscious.

Ah traps.  GMs love to use them, PCs find them annoying.  Yet they are such an essential part of a dungeon crawl.  Although they can be found anywhere, they are always first thought of in some dark abode of a dungeon.  GMs have to be cautious when applying a trap to their game.  Too lethal, and you run a risk of a PC death or a total party kill (TPK).  Too easy, and the thief is boasting about how simple the place is for the next hour.  There are so many books about traps, some good and some bad, that a GM should have zero problems finding one to use.  However, sometimes those just don’t fit the kind of place we are building at the time.  What if we are out in the forest, but the terrain is very rocky?  Or what if the forest is extremely thick to where you can’t see more than a few feet in front of you?  That boulder trap isn’t going to fit very well nor will the snare trap work very effectively with all the vegetation.  So let’s build the trap on our own.


The first thing to consider is the most obvious question: how lethal do we want it?  This is such a difficult question because we naturally want it to be dangerous and challenging, but GMs really don’t want to kill players on purpose.  We love running RPGs, and with the PCs we would not have an RPG to run.  So the next step would be to look at the character sheets and take note of all their health whether it is in the form of hit points or wounds or whatever.  If the trap is leading up to something they have sought for, for quite some time and is highly important, consider shooting to take out about 25-30% of their health with a trap.  Naturally damage will fluctuate depending on system, but we are talking slightly below a third of their health.  That way, they could theoretically spring 3 traps and remain barely alive assuming no other ill fate befalls the group in that time.

If the trap is going to be more of an inconvenience that sets them up as slightly wounded for the upcoming encounter, then only about 10% of the health should be necessary.  That way they aren’t going into the fight fully healed, but they aren’t going to get wiped on a single hit.

Once we determine whether to set the traps to stun or kill, we need to brainstorm the concept of what would fit in the particular location that is aesthetically sensible.  For this exercise, I’ll go away from the traditional hallway dungeon as my environment and instead create one for a tavern.  That’s right.  For those who try to steal the extremely expensive and rare Blue Dragon Ale, they will have to face this trap of doom.  And for this, we’ll shoot for the hazardous level at about 25% of their health.  Traps we typically enjoy can be re-used if we set the damage to a percentage rather than a set number of dice.

  • Trapdoor into a container of acid below the wood planks
  • Wrought-iron chandelier collapses on their head
  • Panther uncaged from backroom
  • Spring-loaded blade from behind counter
  • Bag of scorpions or venomous ants
  • Animated zombie head
  • Thousand needle spring
  • Extreme sonic boom
  • Extreme bright light
  • Giant mouse trap
  • Rope snare attached to weighted pulley


I like the idea of a panther being caged in the backroom of a tavern that no one knows about.  The cat is almost always silent, and it moving through the tavern would be equally quiet.  There would be no time for surprise from the thief.  However, let’s keep the trap mechanical in nature and use a combination of the spring-loaded blade and the trapdoor as a secondary trap.

The blade is going to be hidden under the counter top, so unless the bartender is either a giant or a Halfling, it will be around 3 feet off the floor.  This would hit most targets below the belt, somewhere on the legs.    Realistically this would be good to keep the 25% health in mind.  It might cause them to lose a leg until magical restoration.  We could make it more lethal by adjusting the locations of the bottle.  If it is sunk into the ground under a small trapdoor, the perpetrator would be kneeling to reach down.  A blade to the upper torso is far more lethal, even if you are just counting hit points.

The trapdoor could be wide enough to fit an adult human, suspending a small board for the box containing the bottle.  The blade would be the first part of the trap, but the second part would be after succeeding in avoiding it.  Dodging the blade on instinct doesn’t usually bode too well for their environmental surroundings and they simply dive in a direction away from the danger – in this case, the trapdoor in front of them.  Cover the acid with a sheet of cloth to hide what’s below the platform might catch them off guard as they will smell the acid but not identify its location.9

I seldom see double traps, but I try to implement them into my games.  They are essentially a GM’s “Plan B” to the easily succeeded trap avoidance by the PC.  There are ways of combining two or more traps in succession in order to cause more chances to fail.  For example, the box containing the bottle might have the animated zombie head that attempts to bite the thief and inflict its disease into him.  Avoiding the creature by moving their hand out of the way quickly, bumps into the hidden trigger that sets off the thousand needle trap, imbedding tons of little prickly spears into them.   Either put them in a situation where moving is one option to avoid the trap, or give them an ultimatum to which neither are great choices.  Not all choices they have are going to be ideal.  Sometimes they are just going to get screwed, and they have to decide which kind of screwing they want.  The chandelier is falling, but they know the only direction behind the bar they can go is across the open pit of acid that they now have to jump across.  The giant mousetrap for humans doesn’t pin them down but launches them across the air and into a shelf which contains a jar of venomous scorpions.  Don’t be afraid to give them the 1-2 punch when it comes to danger in a game.  Just because they avoid one bad situation doesn’t mean they can’t go through a gauntlet.

You can even have a trap within a trap.  You’re standard spiked pit trap could be spring loaded, sending the victim back out of the pit, which is great, but the momentum points them onto a few sleeping manticores.  They must try to twist their body like Super Mario to alter their trajectory or try to land on a single tip toe between the sleeping beasts and acrobat through their momentum beyond them.


Traps are great for railroading unsuspecting PCs.  If you make it look like a trap but include a difficulty that is highly challenging, it will look more natural.  That collapse in the tunnel that makes them turn back, the explosion in the forest that collapses trees, a sinkhole that opens to another tunnel, spilled acid from a cauldron that opens up a new path to temp an alternate route are all possibilities.  Sometimes temptation is a great way of diverting the party in the direction you want by placing an obvious trap that is in their way.  They can try to disarm it, but it will be extremely taxing and time consuming.  Meanwhile they notice another route in a slightly different direction.

Feel free to make traps that are more as an oddity than a conniving weapon.  For example, the floor gives way to the party falling into a cage below the surface unharmed, but it is suspended above a huge pig pen.  Other cages are suspended with victims in as well; giving hint there are numerous trapdoors in this complex.  Cages begin to lower into the pig pens one at a time and are opened to starving pigs that begin gorging on the other victims.  Their cage never lowers, and the roof of the cage remains open to the tunnel they were traveling in.  It is merely a visual of what might happen in the future if they aren’t safe.  Another situation could be a door that triggers a lock, keeping them trapped inside for a few minutes while a mechanical puppet show springs to life in a nearby nook and tells the tale of the history of the abandoned palace they are exploring.  Make PCs feel they sprung a trap, but you don’t have to always make it damaging.

Until next time, lie about your dice roll as much as you can get away with.  Thanks for stopping by.traps


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