Feb 01 2012

Encounter Building in Pathfinder

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A couple of my friends have mentioned being a little shaky on the process of building encounters in Pathfinder, which is probably a residual effect of the “WTF?” model of EL/CR in D&D 3.x. So I figured I’d write up some quickie notes for it here.

The good news is, you don’t need wonky calculators or bizarre algorithms to build encounters in Pathfinder. It’s an easy-peasy three-step process and can be done with a pocket calculator or even just a rough eyeballing. There’s a nice summary right here on the d20pfsrd site, but I’ll go ahead and write it up here anyhow.

Step One: Average Party Level

This is just what it sounds like, the average level of every member of the party, rounded to the nearest whole number. (So, for example: Ftr 3, Clr 2, Rog 3, Wiz 3 = 11/4 = 2.75 = 3.) There is one wrinkle to this:

  • If the party is 3 or fewer characters: APL = APL-1.
  • If the party is 6 or more characters: APL = APL+1.

For the purposes of building an encounter, the “party” consists of any characters who are going to help the PCs. So if the local constabulary is going to come running to the PCs’ aid (say, four level 3 warriors), they should be factored in. Thus, using the sample party above, the final APL would be (Ftr 3, Clr 2, Rog 3, Wiz 3, 4*{War 3} = 23/8 = 2.9 = 3, +1 for being 6+ characters =) 4.

“Well hold on,” you might say. “All those disposable NPCs only add an effective +1 to the APL? But I want a big fight that will tear them up!” Well that’s easy enough to deal with. If you’ve got a party full of redshirts that you don’t mind obliterating in order to make the encounter big and dramatic, you simply up the challenge rating (CR) in the next step.

Step Two: Challenge Rating (CR) and XP Budget

Encounters are rated as “Easy,” “Average,” “Challenging,” “Hard,” or “Epic.” In any given adventure, most (but not all) encounters should be either Average or Challenging, with a few Easy ones thrown in for variety, then trending towards Hard as you build up to a climactic finish. You should only use Epic encounters very sparingly, because they will almost certainly kill PCs.

Once you’ve determined the APL in Step One, determining the encounter CR is easy:

Encounter Difficulty CR
Easy APL-1
Average APL
Challenging APL+1
Hard APL+2
Epic APL+3
CR is expressed as a whole number for 1 or higher. CR 0 = “1/2”; CR -1 = “1/3”; CR -2 = “1/4”.

Thus, for our example APL 3 party, an Average encounter would be CR 3, while a Challenging encounter would be CR 4. An Epic encounter would be CR 6 and might very well be a TPK.

Once you know the CR, you then use that to figure out your XP budget. You’ll use the XP budget to “buy” critters or hazards to put into your encounter.

CR XP Budget CR XP Budget CR XP Budget
1/8 50 6 2,400 16 76,800
1/6 65 7 3,200 17 102,400
1/4 100 8 4,800 18 153,600
1/3 135 9 6,400 19 208,400
1/2 200 10 9,600 20 307,200
1 400 11 12,800 21 409,600
2 600 12 19,200 22 614,400
3 800 13 25,600 23 819,200
4 1,200 14 38,400 24 1,228,800
5 1,600 15 51,200 25 1,638,400

So for our sample party, a Challenging encounter (CR 4) would have a budget of 1,200 XP.

Step Three: Build the Encounter

From here, you simply “buy” critters, hazards, skill challenges, etc. with your allotted XP budget, starting with the most expensive item first. Everything than can be an encounter element should have an XP value (listed right in the stat block for things that have a stat block). For instance, say you wanted our sample party to have a Challenging encounter with an ogre and his goblin cronies. Your XP budget is 1,200, so you might then build the encounter like so:

Encounter Element XP Budget
Ogre (CR 3) 800
Goblin Adept 2 (CR 1/2) 200
Two Goblins (CR 1/3) 270 (135 ea.)
Total XP Value of Encounter 1,270 XP

Yes, it sneaks over budget, but not by much, and you can always mitigate that with environmental conditions (perhaps the goblin cronies run away at 1/2 or fewer hit points or as soon as one is killed, for instance).

Encounter Design Philosophy: More Bang for Your XP Buck

The way the d20 system in general works (and to some extent, the way all tabletop RPGs work), you’re almost always worse off outmanned than outgunned. So don’t use a single CR 4 opponent to build a CR 4 encounter, because the PCs will quickly swarm over it and stomp it to jelly unless you’ve really beefed it up. Instead, think in terms of encounters with multiple foes, such as the ogre and goblins example above. Granted, the goblins in the example are mostly speed bumps that will probably die in the first round or two– but that gives the ogre another round more than he would have had to be interesting on his own.

Remember also, that Average and Challenging encounters aren’t there to actually defeat your players. They’re there to whittle ’em down. “Resource management” is a big part of the D&D/Pathfinder game system. It’s not the ogre that finally defeats a PC… it’s the cure spells the party ran out of in the last room.

More Encounter Design Philosophy: Making the Most of Minions

One downside of XP budgets is that you always run out of XP way before you have what you feel like are enough critters. Especially after you’ve noticed that critters that are a CR of 2 or more levels below the APL tend to have a really hard time hitting PCs with much of anything. What to do? We need some “minion” rules for this!

…Well, no, not really. It actually works fairly well with just a bit of tweaking.

First, if you have 9 kobolds swarming over a PC, for the love of Mike, don’t roll nine d20s hoping one of them will get the 20 they need to hit that PC. Have six kobolds use Aid Another instead of attacking directly: suddenly you have three kobolds each with +6 to hit, which is much more dangerous!

Second, use your minions where they’re most effective, i.e., going after the squishy party members. Nine kobolds swarming a fighter = nine soon-to-be-dead kobolds. Nine kobolds swarming a wizard = a wizard who’s in trouble. Three kobolds grappling a wizard with +6 = a wizard who is completely shut down.

That said… don’t bother adding elements that are CR-5 or lower to an encounter. Or if you do, treat them like flavor text and don’t actually bother with the math involved.

Rewards (Experience, Treasure, etc.)

This depends on your campaign model. The default is to divide the XP value of the encounter equally among those who participated in it. To keep characters in the general vicinity of the expected wealth per level, you should also either place treasure in the encounter (“Loot the bodies, yay!”) or arrange for the party to receive the appropriate amount of treasure as a quest reward (“The ogre and his goblin cronies didn’t have anything but fleas, but the duke had a price on their heads of 1,000 gp!”). The amount of treasure each encounter earns varies depending on the Slow/Normal/Fast XP option chosen for your campaign, and that info can be found here.

And There You Have It!

Really, that’s it in a nutshell. Very simple– much simpler to do than it actually was to write down. There’s more nuances and all sorts of add-on topics, particularly on the topic of ad-hoc APL or CR adjustments for terrain, gear, etc., but most of those boil down to judgement calls anyway. If you’re fighting ice giants in a lava pit, guess what: their CR is actually much lower than it would be if you were fighting them in a blizzard, and you should adjust accordingly. Similarly, if that ogre is armed with a +4 vorpal humanslayer… he’s probably higher than CR 3.

So get on out there and build some encounters! ;)

-The Gneech

2 responses to “Encounter Building in Pathfinder”

  1. Jakebe says:


    That’s highly valuable advice, and I guess one reason my brand-spanking-new level 1 party nearly got shut down by a pack of five wolves. It turned out to be an epic encounter in which two of our PCs were dropped to zero HP.

    I’ve found that the encounter design right out of the book can make things a little thin, especially when you’re including cannon fodder NPCs, baddies that are meant to distract attention away from the big bad so he can get off an awesome effect or two. Your suggestions should go a pretty long way towards mitigating that. Thanks again!

    • The Gneech says:

      Ouch, yeah! A single wolf is a CR 1 critter, which is an “average” encounter for four 1st-level PCs. Five wolves is waaaaaaay too many. You could do two wolves with the “Young” template, or three “dog, common” and just describing them as wolves.

      And you’re welcome! :) I hope it helps.

      -The Gneech