Running Gloamhold: The Illusion of Detail


In a large dungeon or megadungeon (such as Gloamhold) you (the GM) can never be perfectly prepared. No one has the time—or I suspect the patience—to prepare hundreds of different encounter areas.

When the PCs are in danger of wandering out of the area the GM has fleshed out, disaster looms. At this point, an inexperienced, tired or stressed GM can panic and either the session comes to a juddering halt or the quality of GMing plummets as a series of badly-thought out, boring encounters ensues. Neither situation is ideal.

The tactics below can help you create the illusion of detail in your dungeons without flogging yourself to death preparing countless areas and encounters. Using a mix of the tactics below helps you maintain the illusion of extensive design and detail, and helps the players maintain their suspicion of disbelief, until the end of the session.

Random Encounters

The wise GM has a small pool of detailed random encounters to hand. Such encounters enable you to slow down a party’s progress, if they are heading in a direction you’ve not yet detailed. The encounters don’t have to be particularly deadly, they just have to slow the players down (and, of course, easy encounters are good for the players’ morale).

Dungeon wanderers (gelatinous cubes, darkmantles and so on) or even other bands of adventurers make great add-in encounters. Chance encounters with other adventurers don’t even have to end in combat and can—instead—be an opportunity to make new friends, learn new rumours and so on.


The actions of burrowing monsters, the side effects of powerful spells or even just earth tremors and earthquakes can temporarily block off access to part of a dungeon. If it has rained recently, flooding can also create an area of all but impassable terrain for low-level characters. Once you’ve prepared the relevant dungeon sections, remove the blockage—the flood waters subside, the powerful spell effect wears off, someone (or something) clears the blockage and so on.

Powerful Monsters

As effective as a blockage, placing a monster or pack of monsters the party know they can’t defeat in their path is a great way of diverting a rampaging band of adventurers. Use this tactic carefully and make sure to clearly “signpost” the upcoming danger when using this tactic. For example, the PCs could see the powerful monster from a great distance, discover the smashed and torn bodies of those it has already slain and so on. Remember, if your PCs don’t realise how powerful the monsters are, things can go horribly wrong so give them ample opportunity to retreat (or to bravely go somewhere else).

Sub-Levels and Side Complexes

Dropping in a small side complex of rooms, or an access point to a self-contained sub-level can divert the party long enough to give you time to prepare the as yet unprepared area they were moving toward. These small “mini-dungeons” don’t need to be fully fleshed out—you just has to have enough details to wing it. The players will likely never know as long as the monsters and treasure make sense in relation to the rest of the module.

Cry for Help

In a similar vein to “Random Encounters” above, the party might encounter someone who desperately needs their help. Perhaps, they encounter an escaped prisoner or slave who needs to be escorted to the surface. Alternatively, they could come across a lone adventurer searching for his companions who just happened to go missing in the part of the dungeon the GM has prepared. If you use this strategy, be sure to reward the PCs for their aid. The NPC might even become a regular fixture in the campaign!

Dungeon Dressing

I love dungeon dressing. I love it so much Raging Swan Press released a 300+ page book (GM’s Miscellany: Dungeon Dressing) devoted to the subject. In the context of the illusion of detail, dungeon dressing fulfils three important roles. It help you:

  • Slow down the PCs (as they investigate the mutilated body, strange graffiti daubed in blood or whatever)

  • Add depth and verisimilitude to the dungeon, which his always a good thing.

  • Set up upcoming encounters (see “Random Encounters” and “Powerful Monsters” above).

Final Thoughts

When using these tactics, don’t use only one or two. Mix things up a bit so the PCs don’t realise what you are doing. If they keep meeting blocked or flooded passageway, they may start to suspect what you are doing. Using a mix of the above tactics helps you maintain the players’ suspension of disbelief and keeps the session running smoothly while creating the illusion you are a heroic, thoroughly prepared omnipotent GM who unending slaves over your campaign.

What do you think? Do you create the illusion of detail in some other (cunning) way? Let me know, in the comments below.