Adventure Builder11/03/2006

Terrain, Hazards, and Traps
Part 6 of 6

You can spend a lot of time working on stat blocks for an adventure. But you can have just as much fun, and create a much more challenging play experience, if you spend at least a little of your design time working on the environment. After all, in fantasy books and movies, you hear about the bitter stone lands of Mordor or see the flaming geysers in the Fire Swamp of Princess Bride. Not every challenge comes with fangs or a sword.

The environment provides more than just encounter variety; it also gives rogues a chance to show off their skills, gives fighters tactical opportunities in combat, and --- well, okay, arcane and divine casters don't like traps and difficult terrain. Tough luck. They can dispel certain magical traps and hazards, and that's usually about it for the scroll and holy symbol crowd.

As a designer, you gain adventure depth and richness from the environment design work you do. I think about environmental challenges in terms of broad solutions, channeling movement, and story effects. We'll look at each in turn.

Unfolding Terrain for the Whole Party

Hazards and terrain don't necessarily have to look nasty to begin with, and they don't have to use the usual rogue skills to be interesting. The things that look safe may require Survival checks to reveal their true danger. This gives rangers, barbarians, and druids a way to approach terrain hazards. Consider the following:

  • Crevasses in a snowfield
  • A natural cliff face that looks like an easy climb until the eagles' fish guts and dropping make it suddenly slick and dangerous
  • Geysers that erupt every few rounds, soaking everyone nearby
  • A run of rain-slicked stairs
  • A river crossing with swift-running flood waters
  • A cave floor covered in bat guano that acts like quicksand

That last one is a hazard that fighters might have the best luck with, as it could require either a Jump check or raw Strength to escape.

All of the above could be added to existing encounters to provide more options in combat. In fact, most hazards should be built with tactics and miniatures combat in mind: pools of superheated mud for bull-rushing enemies into, a tilted floor around a pit of snakes, and ground that crumbles beneath the PCs' feet (and eventually vanishes entirely). Many of the obstacles and hazards that make combat interesting should be designed with fighter class skills in mind: Climb, Jump, and Swim. A few should always be magical (magical fogs, guards and wards, permanent cloudkill spells, runes, etc), so their auras can be detected and disarmed by the spellcasters.

This isn't to say that hazards and traps aren't for the rogues in the party. Deliberate magical or mechanical traps will usually require rogues and arcane casters to defuse, but anyone with a few Spot ranks can see the teetering boulder and landslide that giants threaten to unleash on the party. A ranger might notice footprints near a pit trap, and a druid might use a warp wood spell to disarm a ballista trap or open a castle gate that is stuck closed. As a designer, you want to avoid making terrain and traps "just a rogue thing".

Channeling with Hazards and Terrain

If a particular direction on your adventure maps includes, say, a magma field or a necromantic fog, the party may decide that it's not worth overcoming that obstacle. In some cases, that's exactly what you want. When you say "there's a raging wall of fire down the left-hand corridor, and echoing darkness to the right," you're making it easier to go one way rather than another. You're channeling the party with not-too-subtle terrain hints.

For instance, a field full of razorvines in one of the outer planes is essentially a quick way for the DM to say "Don't go there." The party might have a fly spell to go over it (more on that later), but it's just not something that the party wants to burn hit points and cures on. When you are channeling the party in a particular direction, it pays to be obvious.

Even being obvious doesn't always work, of course. Sometimes the party sees the obstacle as a sure sign that some great treasure lies in that direction, or assumes "that's where the adventure is." This sort of metagame thinking can burn a lot of time at the table as the party checks out every dead end. You can either let them continue burning resources until they decide it isn't worth it, or give them an out.

The out could be a helpful NPC, a map, or clue that points in another direction, or even just reaching the end of the hazard – with nothing to show for it. Next time, they may spend a little more energy on scouting or research before they take on the Forest of Infinite Brambles or the Death Fog. It's okay for PCs to learn the hard way that some obstacles are just... obstacles. Smart parties learn to avoid expending their energies for unclear goals.

Hazards for Story Effect

What if you don't want the party to avoid your nasty terrain? Then you'd better make it unexpected, make it exciting in story terms, or just make it clear that conquering the obstacle is worthwhile for them. You can do this with surprise terrain, drama terrain, or luring terrain.

Surprise Terrain: Quicksand and avalanches, rockslides and pyroclastic flows, fields of undead rising up all around, or piercers and green slime dropping from the ceiling --- what do they have in common? The PCs might not see them coming.

Surprise terrain encounters are the D&D equivalent of the "sting" or shocking moment in a horror movie. If done right, they scare the party for a moment, ratcheting up the tension in an adventure, and putting the PCs on their toes for the next one. Note that traps require speed; if you are going to run traps and hazards effectively, you must play them quickly. Nothing frustrates players like hearing "You hear a click, and a trap goes off – wait a second, I've got to look this up." It creates some suspense, but not the good kind. The game is at a halt. People wander off for chips and a soda.

The solution is to do the lookups before the game. Write down the page numbers for special rules like drowning, bull rushing, deep snow, or whatever applies – better still, use bookmarks or copy and paste the sentence you need from the SRD into your adventure. Structure the encounter to be quick and be done. Read aloud one or two quick physical details, ask for the required rolls, then move on. Maybe throw in a blast of music or a sound effect if it matches the encounter type.

How is this "worth it" for a party? It's a fun scare. They might not admit it, but shock value is sometimes part of the fun.

Drama Terrain: Hazards and other "passive" terrain can have a powerful dramatic effect on a party. For instance, the waters of the River Styx can wipe out memory, or a waterfall or cave-in can split the party, or a particular hall may be full of magical echoes and voices from the past. In each of those cases, you've designed in a change to the whole adventure because you've manipulated the situation to change the party's goals. Does a split party continue? Does the scholarly cleric speak with the dead in the hall of whispers – or risk calling attention from incorporeal undead? The description of the terrain affects the party's options enough that it could become a side quest.

The other way to think about drama terrain is to provide the hams and showboat players with a golden opportunity. If a princess is surrounded by a lake of fire, the paladin may step up to rescue her --- and may fry for his trouble. The important design of drama terrain is that you build in difficulty through both the description and through a series of saves or skill checks. A single Fortitude save and some fire damage might be one way to design the dramatic "wading through fire" scene. But it is much more effective if you write three pieces of text: one as the character approaches the danger (the "Are you sure?" moment in gamemastering), one as the character begins to overcome the hazard, and one to up the stakes. The first of these is pretty familiar, and is something like "You feel the heat of the fire and smell your leather boots begin to smolder. Do you walk into the flames?"

The second is a little tougher. The fire damage is automatic since the character is deliberately walking through it, but once you assign the first round of fire damage, you could ask for a Will save to keep going. Even tough guys and firemen know that walking through fire hurts, and some characters might not be able to push themselves through that. So read "Your hair and eyebrows are charred, your eyes water, and your lungs burn. The end of the fire looks a long way off." If he makes the save after that, he's won bragging rights (and if he doesn't, the other players will mock him).

The final bit of drama is when things get worse. Sure, the character was expecting fire damage (a few hit points off the sheet, no big deal). So make it a bigger deal. "You are sinking into the coals on the floor, almost up to your knees, and the straps and wooden pieces of your armor and gear are catching fire; you can barely see. If you continue, the boots may burn right off your feet." If the PC moves ahead, assign more automatic fire damage for staying and then ask for some item saving throws. If he makes it through that, it's a lot more rewarding than just "You take 10 points of fire damage and walk to the island." By playing up the drama with multiple checks and increasing risk, you've made that fire walk much more memorable.

Luring Terrain: Put a big obvious sign that what they want is beyond a section of oozing gassy swamp, or up on a tall, slick pillar, and watch the party come up with clever ways to bypass all your ingenious, lethal, heavy-on-the-saving-throws design. Luring terrain usually requires three things: an obvious reward, a cost, and enough time for the PCs to decide if they want to pay that cost.

For instance, they might hear that a holy sword is hidden in paladin's shrine, and that both forces of evil and of good want to keep it there (for different reasons, of course). When they arrive, they see that the entire shrine is guarded by archons and the sword itself is contained in a pillar of divine light that burns everyone around it – and they see the fire absolutely incinerate a devil that tries to steal the sword away. Do they want to fight the archons? Maybe. Do they want to suffer divine fire? They'll have to do so or find another way to succeed. The terrain in this case is designed to make the party consider bargaining with the archons – leading to a carefully-designed roleplaying encounter – but the party may decide it's worth going the obvious combat route instead. The paladin's ghost may not appreciate their technique...

The Flight Problem

Many traditional traps in adventures are really targeted at walking intruders: the rolling boulder, the trigger plate, the pit full of acid or the moat full of dire crocodiles. They can be avoided by any flying creature. Even castle walls are subject to this problem once the party includes spellcasters with flight spells.

The solution? Flying traps and trapbuilders who are ready for flying trespassers.

A flying trap uses the same elements as a normal trap: a trigger and a payload. The triggers could be tripwires strung from wall to ceiling and painted black, floating seeds or feathers, superthin spider silk, or enormous soaplike bubbles that pop if touched. They could be area triggers: if a certain square is flown through, the aerial disturbance releases the trap. Or they could be like the swarm of bloodhawks guarding Tenser's tower in Return of the Eight; all the villagers know that flying visitors get mobbed by masses of bloodthirty raptors – only fools fight their way through.

What are the payloads of a flying trap? They could be poison gas, darts, crossbow bolts, or explosives, but those are fairly standard. Why not be more original and use ray spells, or a nasty downdraft that forces a flying creature onto the spikes beneath it, or a hailstorm that ices a flying mount's feathered wings? A normal-looking cloud of deadly poisonous spores. There are just as many things deadly to a flying character as to a walking one.

While one or two flying traps or hazards might be appropriate, don't overdo. If a party is burning resources flying around your cunning pits, webs, and oozes – well, at least they are using their PC resources. Those fly spells and potions won't be available later.


Terrain and traps are more than nuisance encounters; they can add variety, drama and spice to your games. Don't forget to add richness to combat encounters and movement parts of the game by the careful use of terrain and hazards to give each adventure area its own sense of place, danger, and mystery.

About the Author

Wolfgang Baur is the co-author of the Dark*Matter campaign setting and dozens of adventures. He offers custom-tailored adventures and professional advice to patrons of the Open Design blog

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