In old-school role-playing games, one of the things that strikes me—and hard—is that there is very little guidance to new players and especially new game masters on how to perform basic tasks related to the game. Solving that problem is one of the goals of The Adventure Guide’s Handbook.

When it comes to wandering monster charts, even the sprawling venerasity that is the Dungeon Masters Guide eschews instructions on making them, and just provides its own charts that include every monster in the Monster Manual plus a few. The only instructions on making your own were that if you wanted to add your own creatures you calculate the experience point values, correlate them to existing creatures, and insert them into the existing tables next to those existing creatures. Thus, every dungeon potentially includes every monster, and every unnamed city/town includes a full complement of harlots.

On its face, making a wandering monster table is as simple as making a table and putting monsters on it. Choosing the appropriate monsters to put on it, however, is a skill that, for me at least, took some time to learn. An area that has a unique flavor is more memorable, and random encounters contribute heavily to how players remember an area. Wandering monster tables shouldn’t just be an afterthought, nor should they be generic to the entire campaign world.

I have found it easiest to break encounter tables into two parts. I use a table of general categories of encounters that breaks out into tables of individual encounters. Here’s the example of a “general categories” table from the handbook:

The break out for Fantastic Creatures might look like:

And the breakout for Natural Encounters might look like this for a particularly wet area:

But how to choose what categories go in the category table, and how to decide what individual encounters belong in the break-out tables?

Think about the area in general. Think about the kind of encounters you want for the feel of the adventures that exist here. Are Fantastic Creatures common? Rare? Is the area well-traveled by caravans, farmers, or brigands? Will they often be huddling in their tents from the damp mist or rolling thunderstorms, or seeking shelter from sandstorms or the blazing sun?

Is there a special category of encounters you want to focus on? Give them their own heading. Dinosaurs in a prehistoric valley, for example, or creatures of the Chaotic Mist in the mist. The rule of thumb is simple: are you thinking that 10% or more of all encounters need to be undead? Then there is an undead section in the list. On the other hand, if you just think, well, the undead are a fantastic encounter along with the others, then it does not need its own section.

And if, even if the category itself is rare, there are lots of creatures within that category, then it might still justify a position in the categories table, to make it clear that while these encounters are rare, you might see a whole new world once they’re encountered. Faerie encounters might fall into this category of rare but rich.

However you choose them, make a list of just those wide categories of encounters, and adjust the percentages. Some common categories are:

• Civilized peoples
• Animals
• Fantastic creatures
• Natural encounters
• Humanoid creatures

And, potentially, special categories dependent on the area, such as dinosaurs, aliens, chaotic mist encounters, masquerades, faerie, or dragons.

Assign percentages appropriate for the feel of the area. If it’s a fantastic area, there should be more fantastic encounters; if it’s mundane, more civilized creatures and/or animals, and if it’s wild, more natural encounters.

Then, start thinking about specific encounters.

Generally, I try to avoid having too many levels of tables.¹ One for general categories of encounters and one for the encounters themselves is perfect. But if a group of encounters is rarer than can be modeled in one table, I’ll separate that off. Dragons, undead, and faeries often end up getting their own third-level tables in areas that are not infested by the creatures enough to warrant their own second-level table.

When looking at what’s in the area, look at your adventure.

• Are there any warring factions in the area? These are the most likely encounters, because they’re on patrol and paranoid.
• In the encounter key for the adventure, what creatures are mobile? What creatures are likely to investigate strange noises or prowl for victims?
• What natural features does this area have? Waterfalls, rivers, streams, and canyons, if common, are good natural obstacles to put in an encounter table.
• What mundane animal and plant life might constitute an encounter?
• What is the weather like? Any inclement weather goes into the natural encounters table.
• Who is traveling through this area? Do caravans pass through? Where are they from and where are they going?

The answer to those questions will fill out your specific encounter tables. If the table isn’t interesting enough yet, I’ll also look at nearby areas and see what kinds of things that live there might be passing through here. And, finally, I’ll glance through the environments section of the Encounter Guide, pulling out creatures that are common to the area as well as one or two—and only one or two—creatures that are at least somewhat unique to the area, to give it extra flavor.

Also, see Constructing encounter tables using Nisus for a percentages-to-ranges macro. I find it a lot easier to adjust and work with percentages than with numerical ranges that need recalibrating every time I change one range. Many of my older tables, before I started working in percentages rather than ranges, have either missing or overlapping ranges.