GM Advice: 3 Reasons to Have Wandering Monsters in Your Dungeon

The PCs should not be the only things to creep through the dark of the dungeon in search of loot and/or prey. Other things lurk in the ebon shadows of the underworld waiting for foolhardy adventurers to wander by…

By William  McAusland
By William McAusland (Outland Arts)


Wandering monsters are something that has seemingly fallen out of fashion in recent years. In the Good Old Days, every module had a table of random encounters. Sometimes for dungeons with several levels, you got several different random tables! Designed to simulate the movement of monsters around the dungeon, they were a fun facet of the game.

Nowadays, however, they seem to be somewhat less common. That’s a shame as they are a vital part of any well designed dungeon and despite popular misconception, they don’t always end in pointless combat. Clever PCs can gain great advantage from random encounters.

There are three basic types of random encounter:

  • Denizens: The PCs encounter denizens of the dungeon. Combat (or a hasty parley) often ensues. Occasionally, the party might encounter slaves or an escaped prisoner. Such encounters often yield valuable intelligence about the layout of the dungeon and its inhabitants.
  • Explorers: The PCs encounter another adventuring group. The other party could be friendly (or not).
  • Scavengers: Some monsters are nothing more than scavengers. They may be tolerated by the other dungeon denizens, feared or actively hunted. Scavengers rarely carry appreciable treasure with them.

For the GM, wandering monsters fulfil several important functions:

  • They Keep Things Random: In a game where very few or no monster wander the dungeon (or other adventuring locale) the PCs can stride the halls with relative impunity. After all they are in no danger as all the monsters are in their rooms. A party that doesn’t have to worry about wandering monsters enjoys a significant advantage over those that must consider such things.
  • They Build Verisimilitude: In almost every dungeon, castle or other adventuring location its denizens move about. To have groups of monsters simply lurking in rooms waiting to be killed is ludicrous (and dare I say it unrealistic). Food and water must be procured, guards changed and so on. It stands to reason the party will encounter denizens going about their daily lives.
  • They Consume Resources: Wandering monsters inevitably consume resources. Thus, they act as an incentive to move quickly and carefully. If the party spends an inordinate amount of time wandering about a dungeon or routinely spends hours searching every area they discover it stands to reason they should encounter more wandering monsters.

Wandering monsters add an extra level unpredictability into any delve. Include them in your dungeon today!

Help Fellow GMs

Do you use random encounters for another reason beyond those listed above? Share them in the comments below and help your fellow GMs use wandering monsters in their games today!

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Creighton is the publisher at Raging Swan Press and the designer of the award winning adventure Madness at Gardmore Abbey. He has designed many critically acclaimed modules such as Retribution and Shadowed Keep on the Borderlands and worked with Wizards of the Coast, Paizo, Expeditious Retreat Press, Rite Publishing and Kobold Press.

13 thoughts on “GM Advice: 3 Reasons to Have Wandering Monsters in Your Dungeon”

  1. If you use wandering monsters I use a mechanic that means whenever the party makes a lot of noise or otherwise makes their presence known I increase their alarm score. This score starts at 0 and the higher it is the more likely they are to encounter enemies/stronger enemies.

    1. Good idea. I’ll pop that on my session sheet. Increasing chance of encounter because of noise, light, fire or food (smells) makes a lot of sense.

    2. I’ve never codified it as an “alarm score,” but when my players start goofing off, or the party splits inside the dungeon for no better reason than the players getting annoyed with each other, the rolls for random encounters increase. In other words, I never thought to increase the odds on the roll, I simply roll more often. My players usually do NOT like when I roll dice they can’t see…

    3. I have used similar before. The party was exploring an underground city infested with shadows and they had tons of fights on their hands because they needed a light spell to see so they kept having groups of shadows coming up to them.

    4. I’m an “old dude” and I recall the Wandering Monster tables from “Keep on the Borderlands” with a certain glee.

      I’ve never stopped using wandering monsters/random encounters as a part of my game. But I have stolen wildly the good ideas of my fellow DMs. The resulting system looks like this:

      1. Every area has a threshold for encounter; closer to the goblin warrens you have a higher risk (4 or less) of encounter than near the narthex of the Forgotten Temple (only on a one). Until today, the system hinges on s d12. But I might shift to s d20 for a greater range.

      2. Tactics and choices affect the threshold (as was mentioned here); a high stealth party gets a -1 or more to the threshold, while the party whose Witch is in love with her Ear Piercing Scream spell may get a +3 or more.

      3. Customize the Wandering Monsters to the adventuring site. Never use tables like the ones in the original DMG to just randomly drop a demon into the tunnels near your goblin lair. Make the charts make sense where level and setting are concerned.

      4. Drop Tables. When it’s time to generate an encounter, use a drop table. The table format I pilfered is here:

      I find it very satisfying in that withjydt a little prep work, I can create unique encounters for my players.

      It can require a bit of crafting to use in that you don’t roll the dice in the usual manner. You want them to move about and create a “living” result. (I made a dice rolling space with a shoebox, tape and some artwork… well, some scribbling. )

  2. I guess it depends what you mean by “wandering monster”. I am not a fan at all of random monsters in dungeons or anywhere else — it tends to make the environment feel haphazard and unrealistic, and tends to be a sign of weak story development. That’s not to say that there can’t be monsters patrolling the halls — but they need to fit, and to have some reasonable purpose there.

    In general, I think random encounters are a bad idea. A good DM will have a bag of potential encounters to help respond to player initiatives when they start to take the story off the rails, but the encounters can and should be used to take the game back toward interesting story.

    1. I think you missed the point here or at least, I did not understood it the way you did. Random encounters doesn’t mean you check on a list of monster and put whatever you roll in said dungeon, I feel the exact same thing about it than you do. But, unless you’r in a dead dungeon, dungeons should thrive with life because of the location and all the advantages such place can provide, shelters, food, darkness(!), etc.

      When you create the dungeon, you should put some thoughts about what could take advantage of such place/location and create a small ecosystem from where you could pick your random encounters.

      If you are in a dungeon where there are guards, it is normal that they are listening, eat, move, you could encounter such moving group for whatever reason which could in fact provide a random encouter….

    2. Random encounters should always be based on the environment; otherwise they don’t work. It’s often a good idea to have some encounters be more likely to be rolled for than others. That said, with both of those criteria met, they are far more realistic than every encounter being planned because you’re going through these creatures’ home.

      Let’s say that I’m running a dungeon crawl through a cave network, and in these caves there lives a tribe of goblins and a tribe of kobolds, with some empty space between them as they tend to fight each other when when they meet. Let’s set up a table wherein I roll 2d6 to see what monsters I get – some are going to be far more regular than others. 2-3 is hobgoblins, 4-6 is goblins, 7-10 is kobolds, 10-11 is another adventuring party and 12 is roll twice; hobgoblins and goblins are on the same side; if you get two results on different sides then they are mid-combat.

      On the other hand, if I’m running a wilderness exploration, then it makes sense that on a 2 on 2d6, a dragon might be what I roll. Just because I’ve rolled a dragon doesn’t mean the players should be fighting a dragon – it could mean that a dragon flies overhead; it sees them but decides they’re not worth the effort to go down and eat.

      Personally, I believe a story is what happens once the game is over – it’s how they remember what happened at the table. Random encounters, be they with a travelling merchant or a band of thieves, help spice the story up providing that they make sense in the context they occur; and if the encounter doesn’t make sense at first, there should be a reason why that can be discovered.

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