Terrible Terrain

Welcome to the third installment of Everyman Gaming’s GM’s Guide articles. In this GM’s Guide, we’ll be talking about terrain.

Irony is a horrible, horrible thing.

 Back when I ran the GM’s Guide to Challenging Encounters, the #1 topic that was ALWAYS requested of me was terrain. “How do I incorporate terrain into my encounter design?” “What are some good ways to use terrain in my encounter design?” “Tell me how to use terrain in my encounter design.” It was (and still is) the most commonly requested topic that I get.

 I never design encounters with terrain in mind. Ever.

 You have no idea how hard it was to sit down and try to give people tips and advice on a topic for something I personally don’t even consider myself. That isn’t to say that I ignore Pathfinder’s terrain rules or run all of my encounters on blank, featureless spaces. But what I am saying is that when I sit down to design an encounter, the last thing on my mind is, “And I’ll place this monster in a swamp because it’ll make the encounter harder!” If you want to know why I think terrain is the absolute least important part of encounter design, read on. If I’ve gravely offended you with my blatant disregard for the forces of nature (because you’re a druid) I understand if you feel the need to close this webpage. I forgive you. (No I don’t.)

Terrain’s Effects on Encounter Design

Now, just because I blatantly disregard terrain when I build my encounters doesn’t mean that terrain has no impact on encounter design at all! According to the the Core Rulebook, placing a monster in a combat that grants it an advantage increases the encounter’s CR by +1 while placing a monster in an environment that grants it a disadvantage reduces the encounter’s CR by –1. This rule is pretty simple, pretty straightforward, and pretty horrible in my opinion.

Why This Rule Is Horrible

I 100% advise against using the above rule when you’re designing combats. Why? Terrain is easy to nullify, especially at high levels. Think about it: you’re in a swamp. Swamps are difficult terrain. Your party has a Level 5 wizard. How many ways can you make the swamp irrelevant? Here’s a short list: feather step, fly, touch of the sea, levitate. None of those spells are higher than 5th level, but if your group spellcaster has access to even one of them, the fact that your swamp terrain imposes difficult terrain doesn’t matter and that encounter that you planned on being CR 7 is now only CR 6, which might not be challenging enough for your tastes. And sure, completely bypassing terrain in this manner is shortly lived (especially at low levels) but gods help you if your PCs acquire a wand of any of these spells or a magic item that provides the spell as a continuous effect. As a special shout-out, you can buy a pair of slippers of feather step for 2,000 gp. Feather step allows you to ignore ALL difficult terrain, and roughly 50% of all terrain is difficult terrain. That encounter is no longer challenging because of one easy-to-purchase magic item. In effect, the more powerful your PCs get the better chance that they can completely ignore terrain as a challenging mechanic.

How I Use Terrain In Encounter Design

  1. I pick the location of the combat, including the terrain. This is important because it helps me set the tone and feel for my combat: a crawl through a forgotten crypt has a different feel then a romp through a wood, and as a result I’m going to use different monsters in each location.
  2. I design all of my encounters. I pick the CR that my players will go up against, I plan all of the aspects of the encounter that my PCs will find challenging. Not once to I even think about terrain during this step, however.
  3. I design the terrain. Step Three is optional: sometimes I wing the terrain and just draw it in wherever I want. (I typically such spontaneity exclusively for outdoor encounters: in dungeons, my terrain is meticulously planned in advanced.) I keep a handy list of potential terrain effects for the type of terrain I’m using and apply them as necessary: sometimes I randomly roll to determine the weather or sometimes I allow the player to unwittingly determine the weather by making a Survival skill check to forecast the weather. Oh those poor, unfortunate players ….
  4. 4.    I run the combat.
  5. I award experience. If the terrain proved to be advantageous to the enemies, I effectively increase the encounter’s CR by +1 for the purpose of determining the XP award alone. In contrast, if the terrain proved to be a hindrance to the enemies, I decrease the encounter’s CR by –1 for the purpose of determining the XP award. If the terrain provided little to no benefit or hindrance, I leave the XP award as-is. In effect, I use the terrain rules after the fact as a reward system for particular deadly combats rather than as a tool to determine the difficulty of my combats before the fact. 

And that’s all I have to say about terrain. For now. What do you think? Is terrain an integral part of your encounter design or do you treat it like I do? Do you think terrain can remain challenging at all levels of play? Do you think that terrain is worth increasing the CR of an encounter for if the players devote arcane or divine resources to negating it? Do you want me to write more about terrain? If so, what types of tips and tricks are you looking for? Leave your questions and comments below and I’ll see you next time for a (slightly) less angry article at GM’s Guide!

Alexander “Alex” Augunas has been playing roleplaying games since 2007, which isn’t nearly as long over 90% of his colleagues. Affectionately called a “budding game designer” by his partner at Radiance House, Alexander is the author of the Pact Magic Unbound series (Radiance House) and a handful of other Third-Party Products. Before founding the Everyman Gaming blog, Alexander gained notoriety for writing the GM’s Guide to Challenging Encounters, which remains accessible to this day. His favorite color is blue, his favorite Pathfinder Race/Class combination is kitsune druid, and he has personally travelled to 11 of the United State’s 13 original colonies. (He’s never been to Georgia or South Carolina, though he’s had plenty of opportunities to go.)  


4 thoughts on “Terrible Terrain

  1. Ooooh, for me terrain can make a huge factor as it can completely re-shape the way the battle is fought.

    For example, we once encountered a dragon in a huge, rocky, barren wasteland-type area with absolutely no cover. This changed the way the dragon might have fought us as it simply performed a bunch of fly-by attacks with it’s breathe weapon. We ended up all having to use fly spells (via a wand) to chase after him into the air, and this turned our fight from a 2D grid, to 3D as we started using Pythagorean’s Theorem to determine movement rates and speeds.

    Another encounter with a dragon and water elemental changed the fight as the dragon would grapple creatures and drag them under while the elemental held off the party. Underwater combat is extremely difficult on the party as most stuff is nearly useless.

    Sometimes something as simple as raised ledges can alter combat. Like a natural balcony in a cave system might have a group of archers firing down on the party while they fight.

    For me, terrain isn’t so much as ‘rubble’ or ‘swamp’ as it is something that can be used to control movement lanes. Something as simple as a gorge or crevice can force the party to come from a certain direction. True, the caster could use spells, to help mitigate them, but unless he’s got a wand, it’s unlikely he’s got enough slots prepared or available to get everyone until higher levels. It’s also kind of a waste to cast so many spells to mitigate simple terrain like that unless the only entrance is heavily defended or trapped.

    I use terrain to add dynamic effects and challenges to an encounter because it not only makes them more fun, but it lets those guys with lots of skills really get to use them. As an example, a Monk I’m playing has made heavy use of Acrobatics to navigate battlefields to get to enemies in hard-to-reach locations and tie them down until the rest of the party could make it up. Like in one scenario, there was a huge circular tower with a winding staircase and an enemy attacking us while flying in the center out of reach. She had cast fickle winds and we failed the dispel attempts to remove it, so my Monk climbed over the railing and jumped straight up to the next level of the stair case and then would climb up and do it again. He managed to get up high enough he leaped off the railing and grappled the sorceress, and disrupted her spells when she tried to escape. The simple inclusion of a winding staircase really stymied the party as we were unprepared for it and we had to run up the stairs while she simply floated up, out of reach.

    As levels increase, most kinds of simple terrain (rubble, crevices, high ledges) become mostly meaningless as characters gain access to fly spells and other terrain bypassers. But the design of a dungeon itself can be terrain, like corners, or walls, or other vision blockers, can seriously reduce the power of the party. As an example, an enemy in a maze-like area that uses Shot-on-the-Run to fire and move away from the party around corners to mitigate returning attacks.

    Also, keep in mind that terrain only increases CR if it has a major effect on the encounter. Example, an encounter with a tribe of Vanara (monkey-people) in the jungle canopies shouldn’t increase the CR as it’s their natural habitat, while an encounter with an entirely land-based party against a group of squid in a flooded underground dark chamber should increase the CR.

  2. Those spells are fine to get around the difficult terrain inconvenience in a swamp. But they give you basically nothing against:
    – dropped equipment
    – being dragged underwater
    – restrictions on weapons if you’re swimming
    – ambushes from below the water
    – poor visibility

    Not to mention a few spells like Entangle that can synergize well with some terrains. I guess if you aren’t going to use the terrain to full effect, then your CR adjustment afterwards is a good rule.

    Furthermore, every spell the spellcaster has to cast to overcome those other issues is a round they aren’t hurling damage about. And what kind of gentle GM gives the PCs ample time to get all the buffs and protections they want? 😉

  3. I kind use the same approach as you do. First I come up with the encounter and then I think of the scene dressing. If it adds extra difficulty then I’d increase the rewards, but it isn’t to often that I start with the terrain when crafting an encounter.

    Or if things are happening in a dungeon I do try and take into account what the original purpose was for the structure. In that way terrain might come into play for me more often. I like my dungeon Eco-systems to make sense in my brain at least.

    The one time I do start with terrain is probably if I’m planning on ambushing my players.

  4. If there’s one thing I borrowed from 4E, it’s terrain. I don’t use battle mats, but there are lots of neat, simple ideas there. The other thing I did was boil down Pathfinder’s dozen-plus pages on terrain into a single table, because I don’t need to be looking through a geologist’s field guide during an encounter. So what’s 4E terrain about? First, yes, terrain can a static challenge, such as combat in water, or combat along a narrow ledge. But way beyond that, terrain can be dynamic. In the swamp, in addition to the water, and the monster, there are pockets of poison gas; each turn when you move, you may accidentally activate one of those, to your detriment. Or when fighting along a ledge, there may be falling rocks. Each round, either you expend a move action to avoid rocks or you take your chances with the die and hope for the best. You can give terrain a challenge rating, deploy as “another kind of monster”, and factor it in from the start into an encounter’s design. Of course, not every combat needs active terrain; that may become silly after a while. But if even a third of them do, players will be more cautious and observant about the environment, and you get to have a ton of extra fun!

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