Taken For Granted
Every DM has a set of encounter tables. Yet no one ever seems to talk about them. I've never seen them mentioned in any set of core books or on gaming blogs. Some modules list them. But no one discusses their importance or offers tips on creating them. It's time to change all that.
What Are Encounter Tables
An encounter table is a list of monsters that PCs could encounter in a given area along with d100 results next to each entry. You would then roll 1d100 and look up your results on the table to see what monster was encountered.
Here is a simple encounter table. Typically, there would be details on each encounter listed after the table as well. For instance, the first monster listed on the table is "2d4 Kobolds". That tells you that there will be two to eight kobolds but it doesn't say what type or how they are equipped. That info would be listed in the encounter details.
|46-55||1d4+1 Fire Beetles|
|66-75||1d8 Spiretop Drakes|
|76-90||1d8+8 Guard Patrol|
|91-00||Esmerelda the Wandering Cleric|
Why Are Encounter Tables Important?
They aren't critical. You can easily get by without them. However, they serve as a list of what creatures are common to the area along with relative odds of encountering each type.
Beyond that, they are an aid to the DM to help come up with level-appropriate encounters for a given area without having to come up with something on the spot. As a DM you have plenty to remember and more to improvise all the time. Anything that can help you out is bound to make the game run more smoothly.
Creating an Encounter List
Fortunately, encounter lists are very easy to create. Make a list of all the creatures that are known to live in the area. Add to that other creatures that you think are likely to be in or wandering through the area. Don't forget non-combat encounters such as wandering healers or patrols from town. You can also have an "encounter" with an object. The party could discover the remains of another party of adventurers that didn't fare so well with an object on one of them that could start a whole adventure. Or they could stumble upon a cave with a teleportation portal to who knows what.
All of the encounters should be within a few levels of each other. The list is just an extension of what creatures populate the area and creatures in an area tend to be of about the same level.
Once you have a list, assign a weight to each entry (the number of times out of 100 that a particular encounter should come up). All of these numbers need to add up to exactly 100 though so when you roll 1d100, all of the results are tied to a monster. The easiest way to do this is to divide 100 by the number of entries you have. Then add or subtract from individual entries until everything totals 100 and you have the distribution you want.
Lastly, describe each encounter with whatever you need to be able to quickly create the encounter from the description. As in the earlier example, "2d4 Kobolds" doesn't give you much. You could detail what type of kobolds and what armor/weapons they are using. Listing what book the monster is detailed in and the page number would be very helpful.
I Have an Encounter Table. Now What?
Having an encounter table for the area surrounding the town that new characters begin in is a good start. When they travel to the swamp south of there, the monsters that they encounter should be different. You will need a new table for that. When they follow the path up into the hills and discover the ancient temple hidden there, you will need a new table for that.
Basically, every large area will need its own table. Many smaller sections of those areas (marsh, forest, hills, etc) will need their own table. Each dungeon should have a separate table. All of these areas are different and players should encounter different monsters in each of them. It can be a lot of work but if you have just one table for everywhere (or even just one for each level or few levels), players will get bored of having the same encounters over and over.
Tips on Creating Encounter Tables
The monster manual has a list of monsters in the back, broken down by level. You could start by making one table for each level. I wouldn't recommend using these tables all the time but instead have them for emergencies when you just need a quick monster of that level. Once you have these tables ready, use them as templates for areas in your world that are inhabited by monsters of that level. Be sure to note which ones are from temperate zones and which live in the arctic, which live on high peaks and which live in swamps. Make sure each list is made up of monsters that you think would live in that area.
Another approach is to go over your maps and define rough guidelines for different areas of your world: level of monsters, danger level (highly patrolled and managed or over-run with monsters) , climate, etc. Then go through the monster manual one creature at a time and decide which areas that creature would live in. Build lists as you go for each area.
A well thought-out and well-placed monster population has a huge impact on your world. If there is a plan behind what lives where instead of complete randomness and a chance of any monster appearing anywhere in the world, your players will see the difference. This is one of those things that breathes life into a campaign. Spend the time and you will see the benefit.