Welcome to the Megadungeon: The Mathy Half of the Master Plan

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Welcome back to the Megadungeon! This is going to be a weird one, kids.

Until now, each of these little design blog article things has had a kind of unifying theme that served as a helpful title for the post as well as to serve as a thread for what we were discussing. But this article? This article is a workhorse. It’s going to be mathy and spreadsheety and it’s going to ramble and be a little bit all over the place. But it’s important.

See, everything we’ve been doing up to this point – absolutely everything – is basically about coming up with a plan to tackle the mapping of a dungeon and the placing of encounters therein. We’re going to hit a point (very soon) where we have a single master plan that will show us the progression of the PCs through the story. Ideally.

And that’s a very important point. Ideally. Hold on to that for a second. Because we’re going to come back to it. Because we’re also starting to get to the point where reality is going to start f$&%ing with us. So, remember “ideally” and hold on for a few paragraphs.

Because first we need to discuss how the NEXT PART of this whole Megadungeon thing is supposed to go.

How to Map a Dungeon

When you get down to it, a dungeon is a simple sort of adventure. Like all adventures, it has a goal (the thing the protagonists are trying to accomplish) and it has a motivation (the reason why the protagonists are trying to accomplish the goal). And, like all adventures, you have a series of scenes and encounters between the beginning and the end that the players have to navigate. If you haven’t been reading my OTHER series on adventure building, shame on you. But we call that a structure. The structure of an adventure is the way all the scenes and encounters join up together.

Well, a dungeon generally has a simple goal and a simple motivation and the only thing between the motivation and the goal is a series of interconnected rooms. Basically, the site of the adventure IS the structure of the adventure. A dungeon adventure – what I prefer to call a site-based adventure – wears the structure on its sleeve.

See, if this were a mystery adventure, we’d have to worry about how to show the PCs that, after they talk to the witness, they could go to the bar next or they could try to meet the criminal contact. But, in a dungeon, it’s as easy as saying “from here, you can go left or go right.”

And that means that once you’ve figured out the goal and the motivation, building the adventure IS building the dungeon. The map is the adventure. Done and done.

But we’ve made things extremely difficult for ourselves. We don’t just want a little adventure site. We’ve decided we want the adventure to be a campaign. A series of adventures. And since we’re planning everything out to provide a balanced, challenging adventure experience, we’ve got to worry about things like encounter balance and XP progression and how much treasure to give out and all of that s$&%.

The point is, we can’t just draw a map and call it adventure design. We have to draw the map of adventure number one KNOWING exactly where it is going to fit adventure number two and three and seven and ten. And so on and so on.

So… the idea is to create molds. To create overlays. And to work from the general to the specific.

So, first of all, we want to understand the overall shape of the dungeon and what the different parts of it are. That’s why we sketched all that bulls$&% with giant trees and caves and things. Because when we map adventure number six and we know it has to connect the root cave to the tree and to the desiccated sanctuary, we know where it has to fit. Otherwise, we end up having to erase day five or day two or something to get things to join up.

But that’s not the only mold. Because we also need to know what stuff has to fit into adventure number six. How many encounters does it need? Does it need to provide a key for adventure number seven? Will it someday have a shortcut back from adventure number twelve? Does it need the lair of a boss monster?

When you get right down to it, we’re not making a dungeon. We’re making twenty-five dungeons and joining them all up. And not just physically joining them up. We are also creating contingencies and dependencies. Room seven of adventure nine is only accessible with a key from room four of adventure twelve and it will allow access to room one of adventure thirteen when opened.

The point is, when we start mapping, we want to be able to crank out 25 interconnected dungeons in one (long) sequence.

And everything we’ve been doing to this point has been to develop ONE thing: a schedule. Our schedule will tell us exactly what has to go into every adventure. What encounters, what story beats, everything. Basically, we’re building a single master plan spreadsheet.

And half of it will be done today. The mathy half. The other half will be done next week. The plotty half.

Starting with Your Constraints

Here’s an interesting question: why am I starting with the mathy half. In point of fact, why has my design work focused so much more on math than plot? I mean, we didn’t even discuss who built the dungeon and what kinds of creatures lived there before we spent WEEKS on figuring out how many of them there were and how much experience they were worth. How can I claim to even give a f$&% about story and narrative if I’m basically building a spreadsheet and then coming up with a story excuse for it?

The thing is, to some extent, it doesn’t matter WHERE you start. You’ve got to do both eventually. I could have had a really cool idea for a dungeon story and then started laying the foundation from that direction. So, the choice to start in one spot or the other is technically arbitrary.

But, I’m a smart guy. You know that. I don’t make even arbitrary decisions without a reason. And there are TWO reasons I chose to start with the mathy stuff. One of which is the title of this section. So, let’s briefly mention the other one first.

The OTHER reason is because, in general, fluff and story is a pain in the a$&. It’s hard to just pull a gestating story embryo from your butt and mold it into a good story on command. See, I decided it was time to write and run my megadungeon. It was a project I wanted to do. It wasn’t driven by any great inspiration. There wasn’t a great dungeon story in my brain that HAD to be told. I basically decided to build a project.

The thing is, a lot of creative work happens that way. Especially if you plan to do it for a living, or at least as a part time gig. You can’t just sit around and wait until you give birth to a bouncing baby pile of fluffy adventure bulls$&%. You have deadlines. You have to create content. You have no choice. So you damned well better develop something and hope you can crap out some fluff for it before you have to turn it in.

Hell, as a GM, you HAVE TO have a game ready for a certain day and time, right? Saturday is game day, you’d better be ready to run something. And if you wait until you’re inspired, you’ll be frantically flipping through your Monster Manual Friday night at midnight trying to toss together a few encounters so you can fake it.

So, unless you already have a story in mind, you don’t start with the story. You don’t start with the fluff. You build every last thing you can and, while you’re doing that, a story will hopefully emerge. And, if not, you at least have some framework for making s$&% up.

But, first of all, whenever you have a project with multiple requirements and multiple tasks, it’s always best to start with the requirements and tasks that have the most constraints. What do I mean? Well, this dungeon project is actually the best example of what I mean.

The story of the game is limitless. You can pretty much make up any story you want and have all sorts of cool things happen. You can include any types of monsters and any settings you want. You can go to other dimensions, the bottom of the ocean, the inside of a volcano squid, whatever. But mechanically – especially the way we’re doing it – you’ve got a lot of limitations. If your PCs are level 3, you can’t build a game that requires them to get through 17 encounters at challenge rating 10 without a rest. You can’t. It just won’t f$&%ing work. D&D doesn’t work that way.

The mechanics of the game place a lot of limits on us. And so, that’s the part that we want to start with. That’s what’s going to constrain the project.

The Ideal vs. the Real

So, we’ve been talking about this idea of a carefully planned, perfect dungeon experience based on math and plans and numbers, right? Well, allow me to tell you something: it’s all a load of bulls$&%. It’s not going to be perfect.

First of all, there’s going to come a day when we need to add an extra encounter to a certain path or move a discovery or some s$&% like that. Or when we simply want to. We don’t want those hellwasps in that room. They need to be over there. But that will throw off adventure seven. And we’re going to have to start breaking stuff. In point of fact, we’re going to find out stuff is already a little broken in just a few short paragraphs.

On top of that, for all of our careful planning and guidance, players WILL break things. They will get off the critical path. They will cleverly bypass an obstacle they needed a key for and end up in the wrong place in the game at the wrong time. Some of the idiots might even die as a result.

Hell, for that matter, one party might have terrible luck with random encounters and end up f$&%ing up the experience curve AND running out of resources because they have a random battle every ten f$&%ing minutes.

And finally, no matter how carefully we plan things, you’re going to get those groups that overextend themselves and find halfway through day two that they have to retreat and sleep. And they will screw up the beautiful narrative pace of adventure two.

And none of this is a problem. It’ll happen. And it’s fine. That’s part of building games. Accepting that any given set of my players might break it.

BUT that also isn’t an excuse for not trying. I’ve had a few people raise concerns in the comments that planning to this degree is a fool’s errand because you can’t guarantee success. And it’s true. You can’t guarantee anything. And if you try – if you basically build a linear corridor and lock the PCs in until the finish the right number of encounters – you’re ruining the point of the game.

So, this dungeon WON’T be perfect. It won’t work 100% of the time. But that doesn’t mean I’m not going to try to build to an idea anyway.

A Quick Note: On Days and The Last Day

Hey! The Angry GM here! Here’s the thing. As I went through my final revision of this piece, I realized that there’s two important things that got left out. But because of a major f$&% up, its down to the wire and this won’t get posted on time if I try to do a rewrite to fit them in.

I’m usually pretty good at explaining s$&%. I like to think so anyway. But as this project has gone on, a thing happened in my brain and I forgot to explicitly explain it. The thing is, I have been breaking down the dungeon by “days of adventure.” And we talked about why that’s a good way to plan way, way back. BUT… it’s also important to note that that designation is actually JUST a planning tool. It’s just a convenient way of breaking the dungeon down into chunks.

The party might or might not do all of day three in a single day. They might retreat, rest, and come back partway through, as I mentioned. Or they might get distracted by a side path and take on a few optional encounters before they return to the critical path of day three. That’s all fine. In fact, that’s part of the fun. Remember, part of the challenge of dealing with a huge challenge like this is managing the resources needed to get through it.

The point is that I’m stuck referring to things as “day one” and “day seven” because it’s a useful structural tool. But you should no longer think of those as days of game time. They COULD be. If the party does things perfectly and does everything in the right order, they could actually hit every day exactly when they are supposed to and finish the dungeon on day 26. But that probably won’t happen for every group. Or even most groups.

So, from here on out, a “day” is a specific chunk of the dungeon. That’s all it is. It’s just a useful way of breaking the dungeon into manageable, bite-sized pieces. Day seven refers to the seventh chunk of X many encounters that comes after this gate and before that milestone. It’s just a label. It doesn’t relate back to the rest mechanic anymore.

I also should note that the spreadsheets below have this ominous red line called “the last day.” The Last Day is the final day of the adventure. It’s the end. The final encounter. The party enters Tourian or the Joker’s Party or the Kiln of the First Flame. It’s the point of no return. And, as such, it actually lies outside the progression. It doesn’t matter what happens on that day because that day begins when the party crosses some sort of point of no return and it ends when the party wins. Or dies trying .There’s no math associated with it.

Anyway, that’s all. Two side notes. And now back to the post.

The Mathy Half of the Master Plan

Okay, let’s get down to this. Let’s build the math half of the master plan. It’s actually pretty easy because we’ve done most of the work. We just need to do some tweaking and expand a few things.

Do you remember this:

Planned Progression

That’s right. That’s from Day 1 of this project. That’s when we started planning out how many encounters and how much XP our dungeon was going to have.

How about these:


That’s right. That’s when we were planning out how to compute XP for our megadungeon. And that lead to this, right:


Okay. That was everything we needed to determine the XP progression of our entire adventure. Now, let’s talk about our experience progression philosophy.

First of all, we’ve decided that several things are WORTH XP in our megadungeon. If the players defeat an encounter, they earn a certain amount of XP. An encounter doesn’t have to be a monster, but many of them probably will be because this IS a dungeon adventure. Obstacles and traps will also apply. If the PCs manage to get around or avoid an encounter, we’ve decided we’re giving them HALF the XP. They get the other half when they come back and permanently eliminate the obstacle. The reason for that has to do with the structure of the game. We’re assuming the PCs will pass through the same areas multiple times in their explorations. Delving, backtracking, and exploring are part and parcel of the exploration-based megadungeon gig. And that means, first of all, we don’t want them gaining XP for circumventing the same encounter over and over and over. That would make progression tricky. And it would also encourage a very boring mode of play. It would encourage players to leave threats behind them and keep bypassing them over and over. Probably the same way every time. That gets repetitive. And it also becomes more and more trivial at higher levels. The other reason to encourage permanent solutions is that exploration is – essentially – a form of conquest. It is beating back the unknown. Exerting power of the universe. We want that to carry into the way that players deal with threats.

Now, an encounter is a thing we will place on the map. Any old fight doesn’t count as an encounter. Encounters will be obstacles purposely placed in the way of progress. And, because we’re good game designers, they will be good encounters. Contrast those with wandering monsters. Wandering monsters are encounters (again, they need not be monsters, but they probably mostly will be) that will stumble on the players. We’ve talked about how they encourage motion, tell the story of the dungeon, and keep the site feeling alive. Those things, though, are nuisances. They simply waste resources. And, when the players figure that out, they will strive to explore efficiently. In fact, the random monsters provide a counterpoint to the drive to explore. An opposing force that will help drive tension in making choices. Do we sleep here or retreat, do we take the most direct path or explore this side passage, etc. They are worth almost nothing in terms of XP. A paltry 10% of what an encounter of the same difficulty would be worth.

In addition, we have discoveries. Discoveries are what I’m terming the environmental clues that help tell the story of the dungeon. They reveal what happened here and maybe help the players figure out how to deal with what’s coming up. They are your scan data, your audio logs, your game blog entries. And these, too, will be carefully placed around the dungeon. Some will be puzzles. Others will require interaction with the environment or knowledge checks. And still others will just be sitting out in the open. We want the players to want to find those things. Those are the things that turn this thing from a dungeon crawl into an archaeological adventure.

And there’s one other thing that isn’t explicitly on the table: milestones. A milestone is a big story moment. You might call it a plot point or a story beat (what a weird coincidence, eh). Defeating major villains, opening paths, transforming the dungeon. Those are milestones. Those, too, are placed in the dungeon. We’ll specifically call out when the GM should award the players with milestone XP.

The reason we didn’t put an entry for them on the table is… well, we kind of forgot. But we also don’t need to. See, we decided a milestone is worth as much as an encounter. Even if it is part of an encounter. So, when the party opens the floodgates, they get XP equal to one encounter for the milestone. When they defeat Ridley or the Vagina Dragon, they get the XP for beating Ridley or the Vagina dragon AND they get XP equal to one encounter for the milestone of defeating Ridley or the Vagina dragon. The point is, they aren’t rewards for defeating encounters, they are rewards for significant accomplishments in the story of the dungeon.

So, we can insert milestones easily anywhere we want simply by exchanging an encounter for a milestone. So, say adventure day six has 6 encounters. We can decide, if that is the day the party defeats Ridley, that it has 5 encounters and 1 milestone – Ridley being defeated.

But we’ve covered all that. AND we already have spreadsheets for it all. So what the hell are we doing going over it all again. Well, we want a game plan for every single day. We’ve got to take all of that information and put it into one handy-dandy master sheet that will guide all of our mapping and planning. And one that will also allow us to match up our plot events.

But there’s something else we have to make note of. We have encounters, discoveries, and random encounters. Milestones, we’re counting as encounters since we can exchange encounters for milestones easily enough. But we also have TWO DIFFERENT XP progressions in the dungeon. We have the carefully planned XP progression of planned encounters and we have a whole bunch of optional s$&%.

Remember the idea of a critical path? The trail we’re going to hope the players follow through the adventure that takes them from encounter to plot point to gate all the way through to the end of the game? Along that path, there are going to be a bunch of encounters and milestones that we’re pretty sure the players HAVE TO run into. Right? But we also have side passages and secrets. We have encounters that are off the critical path to encourage exploration. And the players might or might not find all of them. If the players are good about following the critical path, they will miss out on that optional stuff. And we still want them to be level 11 by the time they get to the end. If they wander and find everything, we want them to be no higher than level 12 or 13 by the end. And we don’t want them to level up too much ahead of schedule.

Now, we’re going to consider all discoveries optional, by definition. Even if some of them are indeed scattered along the critical path. As for encounters, we’re going to split them between Fixed encounters – those along the critical path – and Optional encounters – those in side passages and hidden in secret places.

But what about random encounters? Well, random encounters are tricky because they are random. But we’re going to be setting the probabilities on those. We’ll have some sense of how many of those the party is likely to run into in one day. But are they optional? The answer is no. Random encounters are actually part of the Fixed XP progression. If there’s a 1 in 8 chance of having a random encounter per hour and we assume adventuring days are eight hours, the party is likely to run into one every day. And that will happen wherever they happen to be. On the critical path or off it. So we have to assume a baseline number of random encounters. Fortunately, the impact on XP is so small that they won’t f$&% with the progression too badly if the party runs into more. It’s almost like we did that on purpose, heh.

So, we have a Fixed progression consisting of the encounters and milestones on the critical path and the random encounters. And we have an Optional progression consisting of encounters off the critical path and discoveries. And we know the value for each and every one of those things. And we’ve projected how many of each of those things need to be a part of the adventure. Can we put all of that data into one big ole spreadsheet and see how it looks?

Damn straight, we can (click on it to make it bigger if you want to):

Progression 1

Now, let’s take a quick look at what is going on in that sheet. Firstly, I’ve broken the adventure down into 26 days of adventure and noted the level that the party will START each day at. When the area of the dungeon I’m calling day 4 starts, the party is supposed to be 3rd level.

The blue columns are just the XP gain per PC per Encounter (or Milestone), per Discovery, and per Random Encounter.

In yellow, we have the fixed progression. The number of Fixed encounters in that day, the amount of total XP for those fixed encounters, the projected number of random encounters and the XP they are worth, the total XP for both Fixed encounters and Random encounters, and the cumulative XP.

The number of random encounters is, right now, just an arbitrary guess. I decided that random encounters will be light for the first two levels, but after that, the party will probably run into an average of two per day.

The last column takes the amount of cumulative XP, compares it to the XP progression chart from the PHB, and determines what level the party is at at the END of that day.

For example, look at day 6. On day 6, the party starts at level 4. They have six planned encounters and run into two random encounters. At the end of the day, they have gained enough XP to reach level 5.

Now, you might already notice a problem. Good for you. Let’s pretend, for just a moment, we haven’t noticed the problem yet and continue looking at the spreadsheet.

The green columns are the Optional progression. We begin with the number of Optional encounters – encounters off the beaten path – and the XP gained for them. We then have the number of discoveries possible in that day and the XP for them. We add the Optional encounter and Discovery XP together, accumulate it, and add it to the Fixed XP. That column, the Cumulative Fixed + Optional XP tells us the amount of XP each PC will have if they find absolutely every optional thing.

The final column runs the same check as before. Compare the XP to the level progression tables to figure out what level the party is at.

So, that means that if the party finds absolutely everything every day, at the end of day nine, the party will return to town with 14,315 XP and have reached level 6.

Now, this spreadsheet is just compiling everything we already decided on with the previous spreadsheets. The number of encounters per day per tier, the number of optional encounters, and so on. Notice that the Optional Encounters and Optional Discoveries columns have no thought. All we knew going into this is that between 3rd and 5th level, the party would make 6 discoveries. So, I just put 6 discoveries, one per day, into that tier.

Now, let’s talk about where things went wrong. Due primarily to rounding things off, making some assumptions about the number of encounters in a day, and the influence of random encounters, the Fixed progression is kind of… wrong. First of all, the PCs gain some levels way too fast. On day four, they are already level 4. And they shouldn’t be until day six. They spend only two days at level 4 and five days at level 5.

Now, that’s not a HUGE issue. Remember our major concerns are to make sure they are level 11 at the end and to make sure they don’t break tiers too early. Remember that level 6 and level 9 are big power jumps because that’s when we’re going to ratchet the difficulty.

BUT, level 5 is a power level. That’s the level when PC’s power jumps. And because of our tiered approach, they will be facing slightly easier encounters at that point. Remember, everything from 3-5 will be a level 4 encounter. That’s part of our pacing plan to make the PCs feel like they aren’t on a power treadmill. From a balance perspective, spending more time at level 5 is not a problem. It will make things easier for them. But from a challenge perspective, it could trivialize some of the encounters.

However, what IS a problem is that the party DOES jump tier too early on in the next segment. They hit level 9 two days early. And worse, they hit level 12 before the last day.

So, we need to do some tweaking. And THIS is why I do everything in spreadsheets with actual formulas programmed in, even though typing this bulls%& out is a pain:


For those of you who don’t speak Excel, that’s how it decides what level you are based on your cumulative XP.

Anyhoo, what we do at this point is jump in and start f$&%ing with the numbers. And I mean that. There’s no finesse. There’s no grand plan. Just the basic rule that a good day of adventure has 4 to 6 encounters in it. I just started playing around with the fixed progression until I liked it. And here it is.

Tweaking Fixed

A few things to note. First of all, there’s a couple of seven encounter days in there. That is outside the four-to-six rule, but I figured it was okay for several reasons. First, they come at the high power levels, so the party can probably handle an extra encounter. Second, some of the encounters are going to turn into milestones anyway. Third, this isn’t quite final yet anyway, so it’s good enough to get on with for now.

Second of all, notice that the random encounters ratchet up throughout the adventure. We’re leaving them out of the first day entirely. Day one is going to be hard enough on first level PCs in D&D 5E. And they become more and more numerous as the adventure goes on. Partly, this is due to the fact that the party will probably be doing more wandering and backtracking in later levels as they clean up the dungeon in preparation for the final confrontation with whatever the last boss is. And partly, this is due to the idea of using the wandering monster tables to show the changing dungeon environment. As the party gets closer to the last boss, the dungeon mobilizes more and more resources against them. We’re going to have to figure out a neat system for wandering monsters that’s easy for the GM to manage, but I’m confident we can do that. So we’ll assume we’ll have such a system.

Finally, notice that – try as I might – I could not fix the fact that level 3 is so short and level 5 is so long. Looking at the numbers, it’s to see why though. The system is designed to get hung up around level 5. It just takes a lot of XP to go from level 5 to level 6. We’re just going to have to work around that.

Once I had the fixed progression working right, it was time to start f$&%ing with the optional progression. And I did basically the same thing. I just started moving and tweaking numbers more or less arbitrarily until I got a progression I liked. I wish I could say there was more to it than that, but there really wasn’t. I mean, there were a few thoughts in the back of my mind, but we’ll come to those in a second.

Because the thing is, tweaking the optional progression wasn’t actually enough. In order to get the optional level progression to work out well (not jumping tiers too early, topping out at 13, spending roughly the same amount of time at every level, cursing level 5), I had to actually screw more with the fixed progression to even things out. And again, it was kind of just f$&%ing around changing numbers. But that’s precisely why we used a computer spreadsheet. We could tweak the number of encounters on day seven and immediately see how that would change the entire level progression – optional and fixed.

In the end, this is what I got (again, clicking on it makes it grow).

Final ProgressionIt’s not perfect. But we already talked about how nothing would be .In particular, if the party is really diligent, they can jump the level 6 and level 9 tier one day early. But I accepted that. It’s not a big deal for one day of adventure in each spot.

A few things to note. Firstly, notice that optional encounters become more and more numerous as the adventure wears on. I did that on purpose. My logic is that, as the party opens more and more of the dungeon, there should be more optional s$&% to find. Further, as the party moves toward the final conclusion, they will start scouring the dungeon for anything they can find that might give them an advantage. And they might be doing some kind of scavenger hunt at this point to find the objectives they need to confront the final boss.

Notice also that most of the discoveries are in the low to mid levels. Again, that is on purpose. As time goes on, the party should come to piece together more and more of the history of the dungeon. But, by the time they end up in the rolling boulder mode of the final act of the adventure, they should pretty much know the story. Maybe they will find an odd last bit of surprising info here and there. But, for the most part, by the time the party hits level 8, they should know what the hell is going on and how to fix it.

Finally, notice that I corrected the very first Level column based on Fixed Level progression. Because I decided to just accept the quirkiness of levels 3 and 5, I just adjusted my plan. Day five is a level 4 day now.

And… ultimately, that’s it. That’s our mechanical roadmap. That’s how we’re placing our encounters and discoveries and stuff. That’s our big ole plan. Next week, we’re going to try and layer a plot progression on top of it.

Oh! And because some people have asked, you can download the actual spreadsheet here.

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18 thoughts on “Welcome to the Megadungeon: The Mathy Half of the Master Plan

  1. Beautiful. Can’t wait to see the plotty half. I’m so eager to buy this whole thing once it’s done and unleash it upon my players. I do hope you are planning on some sort of digital release and not just print, since it’ll take ages to get here on Brazil in the old dead tree format, if it does at all.

  2. I don’t doubt your Excel skill but I suggest you look into the VLOOKUP function to get rid of those nasty nested IF statements. Just plop the level progression table on a second sheet and off you go.

  3. I love this series. It has been quite educational. Although I admit my eyes glazed over when it got to the math part. But I grok why it is there, and the concepts. Which is something that not every GM will care about, which is nice and the most educational part: A dungeon cannot just be a set of random encounters with a dragon and pile of gold at the bottom.

  4. Angry, I believe you created the quirkiness of levels 3 and 5 yourself. By attempting to streamline the XP awards in each tier, you made every encounter for tier 3-5 give 250 XP. The problem is the XP listed in the DMG (page 81) is not linear among those levels. Level 3 is 150 XP, 4 is 250, and 5 is 500 (2x and 3x the previous levels). So by awarding only 250 XP at level 5, you are artificially doubling the time the party spends in that level. Given that each level beyond 2nd entails anything from 13 to 26 encounters, I would stick with the normal XP awards and build each encounter to the appropriate level.

    Great planning tool, in any case, and I am using a similar model (with different XP awards) to plan an upcoming campaign. Thanks for sharing!

  5. These math-centered articles make the engineer in me giggle!
    I just reread all you mega-dungeon posts and they literally made me high (as in… the true meaning of literally).
    Awesome work and train of thought.

  6. I was wondering if anyone had tried to convert this to Pathfinder. Pathfinder does not seem to break down the numbers for Adventures per day the same as D&D does. I tried to do it, but I ended up fudging a lot of the numbers to make them seem reasonable. If any one has any suggestions for a Pathfinder conversion I would love to hear them.

    • Hey pathfinder bro. For about a million reasons I couldn’t make a clean conversion, however I came up with something semi-workable. I’m on slow limited internet and a dumbass smartphone ATM but email me @ dpcucci@gmail.com and remind me to share

      • I have something semi workable also. I came at it from a different angle. I actually used to spreadsheets, but I’m going to see if I can create 1 spreadsheet and then link the information between the 2. I’ll post a link when I get it finished. Thanks for the reply.

  7. Great post Angry, and very timely.

    I’m doing a very similar megadungeon project that started independently but I have conducted a very similar analysis based on my business training…when I see your excel models it thought you might have stolen my brain.

    I’m running into a question regarding what ratio of encounters/XP gain should be on the critical path? That is, how do you ensure that a party will cross appropriate difficulty thresholds (geographically) on the correct adventuring days?

    Perhaps a key difference is that my adventure will have a lot of wandering and discovery. I’m currently thinking only about 1/3 possible encounters will be on a critical path. As such, a party that happens to discover the critical path would be significantly underpowered by the time it crosses the stage-gate (granted this might be difficult) into the next area. Essentially what I need is some way to model the decision matrix for what the average party will encounter before reaching the next gate.

    An example to clarify, lets say the party has 4 paths leading to 100X, with one being the correct critical path. Assuming a blind decision, the average party will take 2.5 paths for 250XP before succeeding – but this will form a rough bell curve with a standard deviation of 92.6 (Yes, I did the math.) This means, roughly one in 6 parties will have less than 157 XP, and another 1/6 will have more than 343 XP. Once you factor in each path having branches, and there being reasons to pick one path over another this becomes very complex very quickly.

    In theory, there should be a way to calculate an ideal ratio of % of total XP on the critical path vs total available XP to maximize control in a dynamic environment while minimizing the ability of completionists to overpower the system. I’m not saying this well, but does the question make sense?

    In short, how do you intend to plan how many of your encounters will be on the Critical Path?

    • I believe he already did in the Fixed Encounters column. The Optional Encounters are the ones off the critical path, along with the Discovery items and any Random Encounters.

      Back to your problem, in order to prevent a party from being underpowered, make sure you have enough encounters in the critical path to get the party to the level you want, even if the critical path is non-linear (e.g. collecting shards of an artifact). On the flip side, to avoid overpowered parties, limit the number of encounters off the critical path so they don’t jump too far ahead.

      It seems the encounter structure you described is akin to a maze, where there is only one correct encounter path to the gate, with multiple encounter dead-ends. As you pointed out, a party can “luck out” and deal with the minimum number of encounters, while another party may wander through the entire maze and find every possible encounter. My suggestion is to award XP for successfully navigating the maze, and not for each individual encounter. This way you will control the XP awards more closely, and can award XP bonus for additional actions the party took while navigating, such as clearing out x% of the place, finding specific information (Discoveries), etc.

      • That’s exactly it. The Fixed Encounters stuff is the stuff ON the critical path. The Optional Encounters are stuff OFF the critical path. Because, I decided the minimum level to beat my dungeon is 11 and the maximum (with optional content) is 13.

        • Thanks for the clarification!

          I think I’m trying to have a lot more of my encounters off of the critical path–make it more maze-like. Players have time pressure from the story, so i don’t have to worry about grinding for XP.

          FWIW, based on my modeling (cough…guesswork…), given pure random chance, players will encounter approximately 50% of the items not on the critical path. Thus, in scenarios such as mine, 62.5% of total available XP will be received by the party. Interestingly, the StDev of actual XP as a % of the target XP has a strict linear relationship to the 0.62 * ((Target XP) – (total XP on the critical path)).

          Thus, in my case, I’m fine with ±25%. So 60% of the target XP value should be on my critical path, and there should be optional encounters for an additional 80% of the target XP, for a total of 140% of the target available.

  8. Love what you’re doing. But I see a big “boring for the players” danger area in the proposed plan.

    Days 8 through 11 are going to be cakewalks. 250 xp is an Easy encounter for level 5 characters, and 1500-1750xp / adventuring day is 1/2 (or less) of the total adventuring day a character can theoretically handle.

    That problem comes from the adventuring day total for 5th level characters being more than double that of a 4th level character. Instead of a group of 3 levels from 3-5, it would have been better to do a 2-4 & 5-7, and 8-10 for different stages. There’s not such a huge weird break that way.

    • IMO because of the way that PC capabilities over an adventuring day doubles for each level gained through level 3, and from 4 to 5, The way to break it down is a band for 1, 2, 3-4, 5-7, 8-10, 11+. Level 1->2, 2->3 and 4->5 is an 100% jump in staying power. Level 3->4 is only a 50% increase. The 5-7 & 8-10, gaining two levels only adds about 50% capability in those ranges.

      For your project, you can work around this fairly easy: Just keep in mind that the PC will be able to spend a single adventure days will be a single day for Dungeon Day 8 and Day 9, and a single adventuring day for Dungeon Day 9 and Day 10. Don’t encourage them to rest in between. They can easily handle it.

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