On the Megadungeon and 5th Edition Play

Numenhalla was designed and playtested using the Moldvay/Cook Basic/Expert set of rules (colloquially B/X), which were optimized for dungeon style play and campaigns. The 5th edition of the worlds greatest role-playing game is designed around the three pillars of adventure, Exploration, Role-Playing, and Combat.

This differs significantly from the pillars of Megadungeon play. Whereas exploration in 5e is about discovery, exploration in a megadungeon is about resources. Combat occurs in a megadungeon often as a failure state. Role-playing in a megadungeon has more to do with “taking the role” of an individual hero, rather then representing a specific character. The challenge is for you, the player, to outwit the megadungeon, not develop a dynamic personality that comes out through interactions with non-player characters.

No one will take your books away if you decide to play differently, but embracing pure mega-dungeon play has a number of tremendous advantages. It allows free drop in and out play, supporting up to dozens of different players. No “catching up on the plot” is needed. Characters are in charge of determining their own risk/reward. Characters have complete agency within the dungeon. The design of such creates constant choices between risk and reward, making player choice significant.

However, 5th edition nearly obviates megadungeon design. Encumbrance is often handwaved, if used at all; this eliminates an entire pillar of play of figuring out how to safely extract treasure from the dungeon. When used, it’s complicated and non-intuitive (E.g. Strength to pounds, coins to pounds as opposed to Strength to coins.) The treasure itself becomes irrelevant because it no longer provides experience. Getting experience from combat means players are disincentivized to build positive relationships with factions. Gaining levels happens very quickly, granting the players powers and abilities that trivialize many encounters. Cantrips quickly remove any sort of resource management associated with exploration. Many of the skills are irrelevant to dungeon exploration.

Thankfully, only a few minor changes are needed. The below are the suggested changes to use 5th edition in a megadungeon campaign.


Experience is only given for combat when the players are attacked. If the players attack neutral creatures or non-hostile or non-attacking beings, or if they intentionally incite creatures to attack they gain no experience from the fight. Players gain no experience for random or wandering encounters.

Experience is given on a 1:1 basis for gold.

Experience is reduced by the difficulty level of the area. Areas are given a challenge rating. Adventuring in an area with a challenge rating lower then your level gives you experience equal to the the challenge rating divided by your level. (E.g. a level 4 character in a CR 3 area would get 3/4 experience. A level 2 character in a level 1 area would get 1/2 experience. A level 6 character in a level 2 area would get 1/3 experience.) This goes for all experience earned in easier areas, no matter what it comes from.

You can carry a number of significant items equal to your Strength. A significant item would be a suit of light or medium armor, a weapon, a bundle 5 of torches, a potion, a vial of oil, a lantern, 200 coins, etc. A suit of heavy armor or a bulky item takes 2 slots. If you have more than 1/2 your slots filled, you are encumbered per the variant rules in the 5th edition Player’s Handbook on page 176. If you are wearing a suit of armor that grants disadvantage on Stealth (Dex) checks, you are encumbered. If you have more than 3/4 of your slots filled, you are heavily encumbered. Let common sense carry the day.

Eliminate the “History (Int)” skill and replace it with “Appraisal (Int)”. Eliminate the “Survival (Wis)” skill and replace it with “Devices (Wis)”. The history of a megadungeon should be discovered, not already known. Survival is useless for the scale of exploration measured in hours and not days. A successful appraisal roll will give you the approximate value of a piece of treasure if it is examined for 1 minute. A successful devices roll will allow you to repair or disarm traps, repair machinery or equipment, or activate or use machinery. In Numenhalla, it will also allow you to install and repair Augatic parts.

Remove Darkvision from Elves, Half-Elves, Half-Orcs, and Tileflings. This leaves Dwarves and Gnomes as the only races that can see in the dark. For an adventure game, it would be tedious to track light sources. Megadungeons are more survival horror then adventure. Trying to survive in a pitch black underground environment filled with nightmares and terrors, light is a resource that must be carefully managed. Removing the ability of the dark to encroach upon the party significantly reduces the tension in megadungeon play.

The following changes are made to the spell lists:

  • Light is a 1st level spell for all classes.
  • Continual Flame is a 3rd level spell for all classes.
  • If Produce Flame is used 6 times, it consumes a first level spell slot.
  • Spells that do thunder damage or cause noise, immediately draw a hazard die roll.
  • Spells require material components. Identify is powerful in a megadungeon, less so if it requires 100 gp in pearl every time it is cast.

Revisions in Play

The above were the initial changes I made when playtesting Numenhalla. I also discovered rather quickly that resources available to 5th edition players rapidly outstrip even high-level basic characters, in spite of the math curve on the proficiency modifier almost exactly matching that of Basic. Characters gain levels faster, have much larger pools of hit points and output greatly increased damage compared to basic characters. Encounters that would be challenging for a 5th or 6th level basic party due to numbers, would fail to challenge an equivalent 5th edition party.

Addressing this has to be carefully balanced against the feeling of character progression. Obviously if you just increase the danger everywhere as the players level, then they really aren't accomplishing much.

The issue is that the megadungeon is an open campaign, and should contain a variety of monsters that provide a threat to players of various skill levels as they advance. Often players will be retreading the same ground, but with new challenges. But the power-curve crawls so high, so quickly, in 5th edition that deadly encounters become trivial to even mid level parties. Whereas because of the lower power curve, a deadly encounter at first level is still a difficult and challenging one for a 7th or 8th level party in Basic.

Philosophically, this comes down to expectations in play. Modern games like 5th edition contain a large component of 'character advancement' as reward. But if the activities in the game don't change due to this advancement, then it's functionally illusory. You are simply rolling larger and larger dice. The activities and opportunities in a megadungeon do change as basic characters advance, they gain more endurance and the ability to address new a difficult problems. This is also true of 5th edition characters, but the scale is simply much, much more extreme.

A basic fighter will have about 6 hit points at first level, 19 at 3rd, and 39 at 6th level. A 5th edition fighter will have about about 12 hit points at first level, 28 at 3rd level and 52 at 6th level. 5th edition monsters have a more gradated curve of damage output in order to handle the higher abilities of the characters. The encounters and areas must also follow this design in order to provide challenge for the players.

Here are my thoughts on how to address the issue.

  • I've separated 5th edition advancement into separate tiers of play. When entering a new area, it becomes 'locked' at the tier in which the party entered. Later, when restocking, the tier can be adjusted. Note that there is no reason for this to be exploitable. You're a human being. If they haven't been to an area other than to stick their head in, then it isn't locked as anything. This is simply a way to address difficulty without yanking the rug out from underneath the players in terms of expectations of growing in power. 
  • Each of these tiers has their own encounter table and monster encounters for each faction and encounter in the area. 
  • Certain monsters and traps will be considered legendary, having access to a higher threat level based on the average threat of the area. This will still allow dangerous things in areas as well as allowing players to return to an area to defeat a tough opponent. 
Adventurer covers level 1-4, Heroic covers levels 5-8, and Super-heroic covers levels 9-12. Higher then 12th level in 5th edition, and you're coming up against the bounds of what a static environment like a mega-dungeon can provide. Basic characters don't even gain hit points past level 8. Note that 12th level is only 100,000 experience, which in Basic games would only allow you to rise to level 6. 

It's suggested for this reason (more rapid advancement, greater power, etc.) that the general experience available for megadungeon play be (severely) constrained. Players shouldn't gain a level every session or two, aiming for a more traditional rate of 1 level every 4-6 weeks to level 7, and then every 8-12 sessions after that. 

For those of you reading the above with jaws struck slack at taking 2 years to get a character to level 8 or 9, that is the way things used to be. It would often take even longer being that tables had 6-12 people in a session and megadungeons often had around 50-60 players. The list of people who've been to Numenhalla is easily that long. 

Megadungeons are about challenging the player through rewarding play experience, rather than rewarding the player with advancement for experiencing play. I love leveling up and getting new powers as much as the next person, but that excludes wonderful styles of play. The above is how I hope to address it.

Hack & Slash 


  1. Will definitely be referring back to this. I like 5E, but have been struggling with hacking in an EXP system that emphasizes exploration and negotiation over KILL EVERYTHING.

  2. It's very good to see you back. It's also very good to see you have been thinking about the great game and that you've advanced the community's practical knowledge again with this post.

  3. So why change all those things in 5e when you can just use a B/X clone?

    1. Well, the majority of people don't play B/X. They play 5th edition.

    2. We could wish that this was not so, but it is unlikely to ever change.


    3. It seems to me that the OSR focus on B/X includes the addition of interesting subsystems and creating rules for game-able ideas whereas 5e discussion involves a lot of what people plan to hack off. Maybe that's because I only read OSR takes on 5e.

  4. Great post as always!
    Just one thing: why not simply change the 5th edition experience table to an old school one? It's the same thing I now, but maybe it's a bit simpler and gratifying for the players.

    1. That's pretty much what I do: I use the lotfp cleric xp table for everyone and the encumberance rules therein also. XP for gold. Very light xp for monsters.

      A few other mods, including O HP death and dismemberment table rolls and the elimination of cantrips and you're good.

      Interesting ideas though!

  5. i play 5th edition but i don´t use the standard XP reward system. I prefer to give pcs a level when the reach a milestone

  6. I've just started a 5e megadungeon campaign (Stonehell), so this is interesting thanks.

    Re XP, what I'm doing is reducing monster XP to 0.2 so combat is generally best avoided, while giving XP for gp at 1:1 as you say. I'm not using a divider by level, since initially XP requirements increase very rapidly in 5e, however at level 11+ XP for gp goes to 1:10 to fit the 5e XP table break there and encourage 11th+ level PCs to focus on other things such as territory development.

    I noticed every player took a race with darkvision, which let them surprise a kobold work crew. I may use more lighted areas in future.


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