Tuesday, September 17, 2013

Help My Game! - Encounter Design, Pt. 1

Recently I was asked by my friends Umbriere, Icyshadow, and Magnuskn to write a guide to designing encounters in Pathfinder (though most applies for Dungeons & Dragons 3.x as well, though the math may be a little different in some places) and so here we go!

Encounter design has become one of my favorite parts of the game and I've talked a lot about encounter dynamics on forums like the Paizo forums. However, I've never wrote anything in-depth on the subject on the forums. Rather, instead I generally gave individual help advice. Today, we're going to try and tackle ALL the encounters you will ever want to design in your games (and we'll do it with a nod to flair and excitement)!

You may want to split the reading into multiple portions if you can't handle reading a lot at once. ^_^

Encounter Building - Overview
In an RPG "encounter" can mean a lot of different things. For the purposes of this guide, an encounter is a scene that is intended to be challenging, exciting, filled with action, or somehow function to draw the player into your game and your story. We'll begin with combat encounters and then later move on to other kinds of encounters in later articles.

Encounter Building - Combat Encounters
One of the biggest hurdles to jump as a new GM is building a good combat encounter. It is as much or more an art form as it is mechanical formula. It's also where most people make their first mistakes with the CR (challenge rating) system. Firstly, let's look at what we generally do not want or look for in an encounter.
The owlbear stood up and roared ferociously, bearing claws and a sharpened beak that could have snapped trees or severed steel. It takes a swipe at the young warrior before it and its claw glances across his armor, leaving little more than a memorable scratch. Then...the party goes, and the owlbear is dead. The combat is over in one-round. Turns out 4 players each pounding their name-brand into the owlbear results in a dead owlbear pretty quickly. The combat ends shorter than expected and it wasn't very epic. You're not sure why. It was a CR 4 creature. The party was CR 4. What happened?
The above scenario is all too common (and I don't mean owlbears are overused). The GM chose a monster based on its CR, and expected the lone monster to make excitement happen, or to be challenging enough to make for an interesting combat encounter. Unfortunately, there are a few things wrong with this fight.

1. The fight isn't very dynamic. It's really just one brutish monster versus the group. This means that it's already veering towards "uninteresting" because it's pretty strait-forward. This is what you might call a routine encounter, in that it doesn't require the party to make any special considerations or think tactically beyond avoiding getting smacked around a little.
It's not fair! I've only got two claws!
I can't fight ALL of them!

2. The monster is at a disadvantage. Though never mentioned in the rulebooks, something scholars of the game refer to as "action economy" is a very real thing. In short, action economy is the relation between how many actions the protagonists have versus the antagonists (like our owlbear). In this case, the owlbear was by itself. It had 1 set of actions to take. The party was 4 players, so they had literally four times the actions during this combat. So the battle quickly became one-sided as the 4 teamed up on the 1. This is often multiplied further in effectiveness due to team synergy (if the wizard buffs everyone else, his action makes the value of the other actions that much greater).

The owlbear is pretty much on par with other creatures of it's challenge rating. It's worth its experience. The catch is that due to the sheer number of players versus the monster, it's very likely that the owlbear never gets to really interact with the group much.

Now let's look at an encounter that gives samples of the things we do want to look for.

The party wanders through the forest. It's dark as the canopy filters the sunlight into eerie beams of light piercing the darkness (dim light). There are no real trails this deep, so the ground is overgrown in many places making movement somewhat more difficult off the beaten path (difficult terrain in many places, especially the root systems of large trees). The forest is still...perhaps too still. Suddenly the sound of rustling leaves and the snarling of monsters echoes through the forest, bouncing off the tree trunks. Worgs are upon you! They rush in from hiding, taking you by surprise (with a surprise round even). A pair of them slowly circle the party, snapping at them with their jaws and using both the party and the trees to make it difficult to shoot at them. The worgs speak, shouting "Haha, look my lovely mate, at what meal we have lucked into this day!", "Oh yes my dear! So much more flavorful than deer again...the pups will enjoy eating out their eyes!"
"We'd like to invite you for dinner!"

The dim light of the forest grants everyone without low-light vision concealment (20% miss chance), but the worgs have low-light vision (as do elves and gnomes). The worgs ambushed the party because they were taking 10 with a +9 stealth modifier and a +5 bonus from being 50 ft. away from the party when the encounter begins, so the party didn't notice them hiding along the trail ahead. The worgs charged that 50 ft. during their surprise round over what terrain wasn't difficult, possibly knocking down the flat-footed party members with their trip ability when they bite them! As the combat starts in earnest they can either press their advantages gained during their surprise or use their speed to dart around despite the difficult terrain in the forest (moving at 25 ft. per move action rather than the 15, 10, or even 5 ft. of the player characters). When the wolves move, the concealment and often cover (from the other PCs or trees) make it difficult to take shots at them from a distance (but it's still probably the safest bet). The battle will likely rage on for a few rounds before the worgs flee, shouting "My dearest, I believe we have picked more than we can chew today. Let us flee until we have the strength of the pack to bring them down!", or if one of the worgs was slain "My dearest!? You two-legged mutts will pay dearly for this! I will stalk you to the ends of the earth until I tear our your still beating heart with my fangs!".
Let's examine this encounter a bit. It's similar to the owlbear encounter in many ways. It's in the wilderness, it's in a forest specifically (owlbears live in forests too), and the encounter is also CR 4 (two worgs are equivalent in XP value to a single owlbear). So where is the difference really coming in?

1. The encounter is more than just the worgs themselves. It takes the entire scene into account and that makes it more likely to be ingrained into the minds of the players. It incorporates the very ground, trees, and dark glow of the forest into the encounter. The warrior or wizard who feels fear because moving through undergrowth to safety, as well as moving forward to press advantage on the worgs, is difficult and draws even more attention to the worg's quadrupedal speed (it also means moving into the undergrowth makes it impossible to 5 ft. step/shift out of the worg's reach without risking getting bitten). The very trees can be allies or enemies (as you take cover behind them to hide, use them to prevent the worgs from charging you, or curse them for blocking your arrow fire).

From a mechanical perspective, it's taking lighting, distance, skills, and perceptions into account. It's taking terrain into account (with areas of normal terrain that you can charge and move across easily, and areas where movement and vision is troubled). It takes into account the abilities of the worgs and translates them as how they would use them to hunt in a living world.

2. It draws attention to the uniqueness the characters and their circumstances.
The elf who can get a clear shot because her eyes adjust to the dim light will feel more gratified and happier about being a elf. The worgs using their natural habitat to their advantage makes it feel like you are being hunted on their turf, which is scary as you are out of your element and inside theirs! The worgs would have a sense of personality even if they weren't speaking, but their ability to speak and their cunning further draws the attention to their uniqueness and the severity of the situation. It also opens an opportunity to allow the party to try to parlay with the wolves instead or even strike a deal with them: "Hold worgs! Eat us and you'll eat for a day! Aid us, and I will ensure you grow fat on ox a day for a week!"

3. The encounter is more dynamic. You'll hear me use the word "dynamic" many times throughout this guide. Being exciting and conveying a sense of energy and life is what we're going for with our encounters. While slugfests have their place in a game (sometimes it's just downright fun to trade full attacks until one guy cries uncle), there is more going on here. The enemies are moving, biting, tripping, taunting, and in a sense interacting with the players in more ways. This keeps the action more exciting, and ultimately helps to draw players and GMs alike into the excitement of the story.

4. More IS more. I love solo-encounters with a big bad. They really set the feel for when something is big, bad, and awesome. But they should really be the exception, not the rule. One of the biggest changes from the owlbear scenario to the worg scenario was the number of enemies doubled. That means the antagonists were doing more, even if what they were doing was less powerful individually. They are taking more actions which draws more attention to them. If one of them is downed, the other still continues to progress the excitement (either by vengefully taking a few more shots at the party until wounded, or by cursing the party as he foreshadows a vengeance that may or may not ever occur).
"I say ol' man! Cry havoc and let slip the hounds of war!"

Nine out of ten times more enemies means more to an encounter than more powerful enemies because of their ability to work together or to make a fight more dynamic. A battle with 6 orcs and a pair of riding dogs is almost guaranteed to be more packed with action than any single CR 4 enemy (especially if those orcs make use of their NPC wealth and use things like nets, reach weapons, alchemical weapons, and perhaps has an adept spellcaster amongst them or something).

Putting it All Together
Let's try building an encounter from scratch. And for this exercise I'm going to use nothing more than the PF Bestiary plus one custom NPC, to show that you don't need to spend hours and hours prepping for games (mostly generic statblocks will be fine). Plus it gives everyone a nice NPC to add to their collection at the end of the blogpost.

In our example, we'll assume that our party is 7th level. That's high enough that a lot of GMs begin getting bewildered by the capabilities of the PCs (casters have 4th level spells, and martials can break down walls with their fists). It's also a level where synergy from parties is getting really strong and players will seem to have more and more powerful resources and can go longer and longer. So with that in mind we're going to build a CR 8 encounter (a challenging encounter) to be a climactic battle at an outpost during one of their adventures. Pretty standard affair really.

We decide that our story involves a group of orcish mercenaries working alongside a goblin tribe under the banner of a powerful hobgoblin warlord. Under the hobgoblin warlord is a group of witches who are either helping him to achieve is goal or guiding him for their own purposes from behind the scenes. So now we have some antagonists, so let's put together a grouping of them!

XP Budget
At CR 8 we have approximately 4,800 XP worth of enemies to account for. So we divide it up like this.
  • 5 CR 1/3 Enemies: 3 orcs warriors, 2 goblin warriors (675 XP)
  • 4 CR 1/2 Enemies:  4 hobgoblin fighters (800 XP)
  • 1 CR 1 Trap: 1 20 ft. wide pit trap that's 20 ft. deep (2d6 falling damage, DC 20 negates)
  • 1 CR 2 Enemies: 1 rat swarm (600 XP)
  • 2 CR 4 Enemy: 1 owlbear (1,200 XP), 1 9th level hobgoblin adept* (1,200 XP)
Total Value = 4,825 XP

The Location
For our climactic scene (probably a battle, but players can surprise you), we have an outpost with a spiked palisade wall with a pair of tall but rickety wooden towers similar to the crow's nest on a ship. In those towers is a pair of goblins who serve as lookouts and snipers with their shortbows (with their NPC gear, we also arm them with a few alchemist fires they can toss over the side at enemies).  Towards the center of the outpost is a large building made out of brick with small windows and murder holes, with some wooden spikes sticking out of large sections of the walls (mostly to deter battering rams, but could be a stage-hazard if someone is thrown into them).

The hobgoblin forces have dug a pit trap and filled it with ravenous rats near the entrance of their little fort. The rats serve a dual purpose as a trap and as a garbage disposal as they eat virtually anything that's thrown down to them. The trap is activated by a lever on the inner wall of the fortress, which one of the hobgoblins typically mans. When not opened, the pit trap looks like a training platform for warriors to practice their skills on.

Inside the largest building in the center is Reiga, our 9th level adept and her Imp Familiar (gained by the Improved Familiar feat) Xalxor. She typically remains inside out of the hot sun and typically is busy playing with her chemistry set. She is mostly left alone by her underlings out of fear of her magical powers and prejudice against the tribal witches in her clan. She is responsible for the outpost but would rather be hunting elven men to add to her harem that she has been amassing to the disgust of her fellow hobgoblins (who don't like elves at all).

The second largest building in the center of our little fort houses Rex, Reiga's pet Owlbear. He's been in locked in his pen in time out after he ate one of their goblin scouts. Despite his extremely irritable nature, Rex is trained for combat and will obey any hobgoblin, giving Reiga priority should their commands conflict.

Three orcs patrol the camp at any given time, while three hobgoblins are at post inside the main building near miss Reiga. Most of the hobgoblins keep their bows at the ready and the orcs with their falchions. The hobgoblins each have a few alchemist fires on hand in their NPC gear totals, and the orcs are each armed with a single skull-flask of Jujama Juice (a potion of enlarge person) that is said to make their body match the size of their rage.

Scattered about the camp are smaller huts made from brick. These huts are similar to stone in their hardness but are vulnerable to bludgeoning attacks which can knock them apart (bludgeoning attacks deal double damage to them).

How it All Plays Out
If the PCs try to lay siege on the camp from the air (such as with fly + fireball spam) then those not indoors and still alive will take refuge inside the huts (which are extremely resistant to things like fireball and lightning bolt), and will wait out any aerial attacks of the sort. If the PCs bring the battle to the ground, the warriors will attempt to draw some of the PCs over the large pit trap, and then one will throw the lever to drop any unsuspecting PCs. Alternatively, a hobgoblin may ready an action to flip the switch to catch a PC in the trap during a charge or some situation where the trap would be harder to avoid or ruin the PC's action.

If the goblins are left unbothered in the towers, they will take pot-shots at the PCs with their shortbows and throw alchemist fires from their nests, with a special attention to blasting anyone who's in heavy armor (who are more likely to resist their arrows). The towers could be caused to fall down by dealing 20 points of damage (hardness 5) to the wooden poles suspending them, causing the goblins and the towers to tumble over (causing the goblins to take 3d6 falling damage and likely go splat).

The orcs juice up on their potions growing to large size and swing their falchions around with reach. Their armor class in this case is terrible but their threat quite high, and these savage warriors fight until dead through their Ferocity racial ability.

If combat is going poorly for the soldiers, Reiga will emerge with to see what all the commotion is and call Rex to deal with the intruders (and Rex is a little cabin-crazy from being in time out and wants to play). Her familiar Xaxel is of particular cunning and will attempt to harry and harass anyone casting spells while his mistress deals with the rest of the party. He will also us suggestion to attempt to coerce warriors into jumping into the rat pit if it's open. Mistress Reiga has no patience for insolence and will begin blowing everyone up with her most powerful spells like lightning bolt, but will try to avoid killing any human, elf, half-elf, or halfling males so that she can capture and play with them later and decide if she wants to add them to her harem of exotic mates.
"Mmm, I want to know what humans taste like."

Reiga's Statistics
LE Female hobgoblin adept 9; Senses darkvision 60 ft., Perception +12; Init +5;
AC 12, touch 11, flat 11 (+1 armor, +1 dex); Hp 49 (9d6+18); Fort +3, Ref +4, Will +7
Adept Spells Prepared (CL 9th)
3rd - lightning bolt (DC 16) x2
2nd - invisibility, mirror image, scorching ray
1st - sleep (DC 14), obscuring mist, protection from good, comprehend languages
Orisons - create water, detect magic, mending, purify food and drink
Str 8, Dex 12, Con 12, Int 8, Wis 16, Cha 12
BAB +4, CMB +3, CMD 14
Feats Improved Initiative, Toughness, Spell Penetration, Improved Familiar, Combat Casting
Skills Craft (Alchemy) +12, Perception +12
Equipment +1 cloak of resistance, silken ceremonial robe, scroll of raise dead

That pretty much wraps up part 1 of this guide. Next time I'm going to discuss building high level encounters, how to deal with lots of NPCs at once, and how to avoid getting overwhelmed by the sheer options available to each NPC and PC! Until then, game on!


  1. This is a really good guide and I'm looking forward to it's completion.

    Something to think about, is maybe a guide on what can be added to an encounter to change it, without making it more difficult. Some people have a hard time incorporating effects like difficult terrain because they just don't know what would be considered difficult.

    Things like bushes, roots, rubble etc. are obvious hazards, but things like furniture, boxes, coins, are often over looked. You might think about a small guide (or table) of hazards that could be incorporated, and possible sources.

    For instance, fog clouds hamper vision, but so too can heavy rain, or snow, or hail. Coming from Alaska, I'm all too familiar with how snow affects vision, but others might not be. Things like swarms of animals flying around in front of a light source might lessen it's illumination area, or reduce it's light level.

    1. These are all excellent points. One of my gaming groups has had to deal with "stage hazards" a lot lately. Particularly due to adventuring in areas of heavy snow which has made being a melee-only character a bit of a nightmare and prevents charging entirely (everything is difficult terrain :P).

      I appreciate your comments and feedback, and I'll definitely try to bring up that could affect encounters. I know that in a lot of my games that I run, NPCs and players alike will do things like turn over tables to get cover, push objects over onto people or things, or pour liquid over the ground to make it slippery (as was the case when one barbarian player attacked a keg of ale to pour its contents over the floor to prevent a big-nasty from charging it without slipping).

      In fact, checking the environment section of your favorite Core Rulebook (or DM's guide) is a good place to find out lots of fun tidbits about dealing with exotic locations (fighting inside a burning building is pretty crazy)!