Building Encounter Tables for 4E

[Reynard]

I started work on a 4E sandbox style, heroic tier game. Part of the creation process is building encounter tables for when PCs go exploring or wandering about on their own. In so doing, I ran across something of a mathematical snag. I though some other folks' perspectives might help me solve the problem.

4E suggests that encounters should range from PL(Party Level)-2 to PL+3. I want to use a single chart for any given area (The Fellwood, frex) for all character levels (up to 10th, anyway). In addiiton, the distribution of encounters by encounter level isn't even -- there are supposed to be more encounters, on average, of the party's level than lower or higher level encounters. The way adventure design lays it out, there should be 1 encounter at PL-1 (or PL-2, I assume; the encounter design rules suggest PL-2 is acceptable but the adventure design rules indicated PL-1 is your low end), 3 at PL, 3 at PL+1 and 1 at PL +3. If this were an encounter chart per level per location, it'd be easy -- roll 1d8.

The problem comes in when trying to build an encounter chart with overlapping encounters. The first thing that's necessary is to even out the distribution and filling in the PL+2 encounter level. Doing this, we can end up with 5 categories -- -1, 0, +1, +2, +3. But the frequency is still a problem.

Below is a brief example of how the chart may look using a d10. I level 1st level off because there is no PL-1 for 1st level (half strength level 1 encounter?)

Enc. Party Level
Level 2 3 4

1 1-2
2 3-4 1-2
3 5-6 3-4 1-2
4 7-8 5-6 3-4
5 9-10 7-8 5-6 etc
d10 roll

The problem with the above is that the "easy" and "hard" encounters are too common, and with the inclusion of PL+2, the encounters will tend to skew toward hard. But, adjusting the frequency creates some strange chart issues:

Enc. Party Level
Level 2 3 4

1 1
2 2-4 1
3 5-7 2-4 1
4 5-7 2-4
5 8 5-7
6 8
7 8
d8 roll

In either case, my goal was to create a singular chart with some "die modified by party level" roll but I can't seem to find the math that would make it work -- with either even distribution or the distribution per the adventure design guidelines.

Also, flipping through the monster manual makes it clear that each encounter is going to have to be crafted; that is, rolling monsters (monster level ranges from PL-3 to PL+7, per the DMG) individually is not likely to be a workable idea. And if you look at the sample encounters in the MM -- I was considering just cribbing them to fill out the chart -- they are, to me, nonsensical and fairly random in the choices of monster combinations.

It's likely that my pre-4E mentality and attempts at simulation are what's getting in my way and there really isn't a solution that both hews to the 4E encounter design paradigm *and* allows for a reasonable degree of randomness, but I thought I'd ask the floor before I threw the whole idea out.

 

[Fallen Seraph]

I dunno about the difficulty math, but as for the monster groups. Do you have DDI? I would if these encounters are generated on the fly have a laptop handy with the Compendium open.

If you got a encounter happening and you know it is Orcs. It is easy enough to find all the Orcs ever made for 4e in a certain level range and add them in (perhaps using Encounter Builder as well for even faster math).

 

[Nymrohd]

The monster manual ready encounters are I think balanced on monster roles/levels more than logic. You will probably have to handcraft the encounters yourself.
As for a way to do make random encounter tables, use a two-roll system? Roll 1d10 to get EL and then roll on the EL table for the encounter. You can spread ELs on the d10 quite well (1-2 EL Level-1, 3-6 EL Level, 7-8 EL Level+1, 9 El Level+2, 10 EL Level+3?)

 

[Jack7]

I'm personally of the opinion that math is hardly the best way to make anything interesting in a role playing game, much less a fantasy role playing game. Math in an RPG makes things easy to understand and control, but very, very rarely truly interesting.

But ho about a chart like this if that is the way you want to go:

d8

1 Easy, 2 below party level
2 Easy, 1 below party level
3 Party level enc. but party outnumbers enemy
4 Balanced and even
5 Balanced and even
6 Party level enc. but enemy outnumbers party
7 Hard, 1 above party level
8 Hard, 2 above party level


Such a chart would make it mathematically fair and balanced, distributively, given some of the factors you mentioned earlier, it wouldn't make it very interesting or really random, but it would be easy to track and to arrange encounters in that way.

If you wanted to make it interesting though consider these additional options

1 Enemy has access to nearby reinforcements, or are cut off and starving
2 Enemy has access to nearby fortifications if they need to retreat
3 Enemy has easy access to re-supply (especially important in encounters where ranged weapons play a large role)
4 Enemy has good communications or bad communications
5 Enemy is skilled at ambush, or is easily ambushed
6 Enemy moves quietly and efficiently, or clumsily and noisily
7 Enemy is very fast or slow
8 Enemy is desperate and vicious
9 Enemy has historical grudge, or is close minded with traditional leadership
10 Enemy open to negotiation, or has innovative leadership


Also in some encounters the enemy or potential enemy is going to be emplaced, meaning he knows terrain and is already in a good defensive posture. Others are going to be in movement from one place to another. Others are going to be moving on a mission and with purpose, others are going to be simply wandering about, maybe looking for a new environment or place to settle. Stuff like that makes encounters very interesting because different adversaries are going to have very different motives and are going to be open to different options. A wandering tribe might want no conflict, or would even consider an alliance for mutual benefit. Soldiers on a mission from one fortification to another or moving from one locale to another in preparation for war or battle will have little patience for strangers, trespass, or "random encounters."

"Random encounters" are really only random when looked at from the outside in a disinterested way, to the parties involved, everybody has their own motivation.

So I consider factors like movement, supply, motivation, race, objectives and goals, stuff like that.

Anywho, good luck.

 

[brocktoon]

create the various encounters for each area from level 1-10.

from there, have a standard die rolling mechanic,
an example

d20

1- remains of a battle/ encounter, minimal treasure found gold / item equal to PL-2
2- Level -2
3- Level -2
4- Level -1
5- Level -1
6- Level-1
7- Level
8- Level
9- Level
10- Level
11- Level
12- Level
13- Level +1
14- Level +1
15- Level +1
16- Level +1
17- Level +2
18- Level +2
19- Level +2
20- Level +3

Now, a specific area might be more populated with nasty creatures, or more dangerous, so maybe it gets a +2 to the d20 roll.

so, for each area, craft 14 encounters from 1/2 to 13th level.

no need to create a special table for each character level for area.

 

[Reynard]

While I appreciate the input, neither Jack's nor brock's responses solve the actual problem: creating an encounter chart for a location that's good for levels 1-10 while staying within the bounds of 4E's math. Randomly determining the level of the encounter and having encounters built for all potential encounter levels is the easy part; the hard part is figuring out if it is possible to not have to roll for encounter level (based on PL) separately than rolling for actual encounter.

I might have been unclear, so i'll give a completely bogus example:

When an encounter is indicated in the Fellwood, roll on this 1-20 chart:

1: level 1 goblin encounter
2: level 1 elf encounter
3: level 2 goblin encounter
4: level 2 elf encounter
...
19: level 10 goblin encounter
20: level 10 elf encounter.

now, assuming the level breaks are at every odd number (1,3,5... 19) and minimum encounter level is PL-2 and maximum encounter level is PL+3 -- we'll forget about frequency of standard vs more or less difficult encounters at the moment, as that's an adventure creation guideline -- what die do you roll with what modifier for PL to get the proper range of options.

In the above example, a 5th level party should be "eligible" for encounters from 3rd to 8th level, or 5 to 16 on the die. That's only with 2 encounters per encounter level, which is a little sparse, IMO.

 

[Mustrum_Ridcully]

So you want one chart that works for all characters in a certain level range?

Have you considered designing the chart in a way so that certain spots can't be reached if the PCs don't have a sufficient level? (or are too high?)

For example, you might have a list of encounters that has 4 encounters per level. This alone is tricky to calculate - theoretically, you need encounters from level -1 to level +13, though of course you can't really create level -1 or level 0 encounters. Whatever you'd do with those, this gives you 15 levels for encounters x 4 = 60 encounters. (Wow, that's a lot.)


Create a table from 1-60, sorting the encounters by level.
We know that the level range for suitable encounters goes from PL-2 to PL +3, which would give us a range of 6 levels. Sounds like we would normally use a d6... But since we have 4 encounters per level in that table, a d6 won't do it. We want to be able to generate 4 x 6 = 24 distinct values. Unless you have a d6, that might turn out hard. (Maybe it would be better to have 5 encounters per level, giving us a 30 distinct "allowed" levels? As an old-schooler, you might actually own a d30! ). You could try to approximate things with 1d20+1d4 or 1d20 + 1d10/2. (Be aware, the more dice you use to generate the distinct values, the more likely it is you get "average" results. There are more possibilities for dice to achieve results in the average range then the outliers. With a very clever selection of dice you might actually be able to recreate the encounter numbers suggested for adventure desigin, but I doubt that'll work.)

Let's assume for a moment you settle for 1d20 + 1d10/2. This give you a value of 2-25. Now you still need to apply a modifier based on level. The final rolling method would probably look like this:
1d20+1d10/2 + 4 x party level -5.
(with
4 x party level = #encounters per level x party level.
-5 = encounters per level + the minimum dice result +1.
to get results in the 1-60 range.)

For a 5th level party you would roll 1d20+1d10/2 +15 (17 to 40).
17 would be your first level 3 encounter (remember to take the "lower then level 1" encounters on your table into account.) and 40 your last level 8 encounter.

Does this help, or does it get confusing*?

(*Because it confused the heck out of me at first, since I didn't account for the fact that while the party might be level 1-10, there should be encounters from level "-1" to 13 if they were all supposed to be in the PL -2 to PL +3 range, and I was wondering why I could cover 60 entries instead of the 40 I assumed first.)

 

[Reynard]

Does this help, or does it get confusing*?

Thank you. That's exactly the kind of thing i was looking for.

Have some XP!

 

[Reynard]

Of course, all of this has me missing encounter tables based on terrain and frequency. I wonder if approaching it from a different direction would be more worthwhile.

Perhaps the key for 4E would be to "level" an area or location and build an encounter chart around that, using 3d6 or 2d10 to get a bell curve where encounters at or close to the area's level would be more likely than those farther away from the area's level.

 

[Spatula]

If you're really going for sandbox style play, I would just throw out the idea of *having* to provide level-appropriate encounters. Stumbling around the wilderness was supposed to be dangerous in old-school D&D; there was always the chance you'd run up against something that was a lot stronger than you could handle. Of course, some areas would be more dangerous than others - maybe the starting area has level 1 through level 5 encounters, but the Mountain of Everlasting Doom has level 6 through level 14 encounters.

The only game change you'd have to make is dealing with encounters that are much lower level than the party, as they are not a threat. In that case, if combat is initiated, just assume the party wins (or maybe play it out, it should be over quick enough) but I wouldn't award XP. Or cut the XP by some percentage.