The concept of a “passive Perception score,” although somewhat derived from the Take 10 mechanics of 3^rd Edition, was introduced in the 4^th Edition of D&D. The basic concept is that, instead of having the PCs make Perception checks to see whether or not they spotted something, you pre-calculate a static value (10 + their Perception modifier) and simply compare that score to the DC of the Perception task.

Frankly speaking, it’s a bad mechanic that got even worse in 5^th Edition.

First, there’s no variation in result: PC A will always have a higher score than PC B, so PC B will never spot something PC A doesn’t see. This not only eliminates novelty (which can be valuable in its own right), the lack of variety is also inherently stultifying, making it more difficult for different players to take the lead in reacting to different situations.

Second, it combines poorly with bounded accuracy. The basic concept of bounded accuracy is that you push all the DCs into a small range with the expectation that the d20 roll will be relevant and then remove the d20 roll. The Dungeon Master’s Guide, for example, says “if the only DCs you ever use are 10, 15, and 20, your game will run just fine.” But any 1^st-level group, of course, will almost certainly have multiple PCs with a passive Perception score higher than 15.

Which brings us to the biggest problem, in my opinion, which is that in actual practice the whole thing is a charade. You, as the DM, will very quickly learn what the highest passive Perception score in your group is, which means that whenever you’re deciding what the Perception DC is, you’re really just deciding whether or not the DC is going to be higher or lower than the party’s score.

There’s nothing wrong with GM fiat, per se, but the passive Perception score ends up being this weird fake mechanic with a bunch of extra bookkeeping trying to mask what’s really happening. “No, no,” says the DM. “I didn’t arbitrarily decide you didn’t spot the trap! I decided that the DC to spot the trap was higher than your passive Perception score! Totally different!”

So, personally, I recommend that you don’t use D&D’s passive Perception scores. For a better way of handling perception-type checks — which can be used in a wide variety of RPGs, not just D&D — I recommend checking out Rulings in Practice: Perception-Type Tests.

With that being said, if you nevertheless want or for some reason need to use D&D’s passive Perception score, there are some best practices you can follow to do so to best effect.

MAKE A LIST

Ask your players for their passive Perception scores, write them down on a Post-It note, and attach that Post-It note to your GM screen.

This may seem obvious, but I’ve played in any number of games where the DM was constantly asking us what our passive Perception scores were, and there’s absolutely no reason for it. Collect them once, then use them instantly every time. Both the pace and the focus of play will be immensely improved.

Random Tip: While you’re doing this, go ahead and grab the PCs’ armor class, too.

Watch out for changing Perception scores. Some spells, abilities, and magic items may modify a character’s Perception score, grant them advantage on Perception checks, or the like. You’ll need to make sure to track this. (And, of course, you’ll also want to make sure you update your list when the PCs level up.)

In some groups, you may also discover that your players challenge surprise. When players see the mechanics being invoked, even if that’s just the DM asking for their passive Perception score, they’ll accept the outcome; but if it’s all being done invisibly behind your DM screen, some players will worry that they’re getting screwed over. “Did you remember that I have advantage on Perception checks in forests?”

The best way to handle this is to (a) make sure you’re getting it right, (b) reassure them, and (c) if it continues, have a transparent discussion about why you’re handling the passive Perception checks this way and how you’re doing it. You might find it effective to make a point of confirming their passive Perception scores at the beginning of each session, and you can also ask them to notify you whenever their passive Perception scores shift during a session.

(The next technique can also help with this, since they’ll at least hear the mechanics being invoked.)

REMEMBER DISADVANTAGE

One of the most overlooked rules in D&D 5^th Edition is that characters who are “distracted” are supposed to be at disadvantage on their passive Perception checks, which means that they should suffer a -5 penalty on their passive Perception score.

I recommend applying this aggressively in any situation where the PCs are not explicitly keeping watch and/or paranoid. Creeping down a dungeon passageway in hostile territory? On watch at night? You specifically said you were going to keep a lookout on the door while Arathorn ransacks the room? Great, you get your normal passive Perception score.

Arathorn, though? Apply the penalty. Also apply the penalty if the PCs are just walking down the street in a friendly city without any expectation of trouble or hanging out at a tavern with their friends.

In practice, this blunts the problems with how bounded accuracy interacts with passive Perception scores. It also encourages the players to be more specific with how they interact with and observe the world, instead of just coasting through the game on auto-pilot. (This is particularly important in making traps work right, for example.)

ROLL THE DC

You can sidestep the system being a camouflage of busywork for DM fiat by assigning a modifier and then rolling the DC of the check instead of assigning a static DC.

Basically take the DC you would have assigned (10 = Easy, 15 = Moderate, 20 = Hard, etc.), subtract 10, and use the remainder as the modifier for a d20 roll. (You can do the same thing with prewritten adventures that list a static DC.)

This is what you already do with Stealth checks, of course, but it may feel weird doing it for something like noticing the rune faintly inscribed on the ceiling.

The point, of course, is to reintroduce variability to the check so that you can make non-fiat rulings. (For example, I can decide the run is moderately difficulty to notice with a +5 check; but I don’t know whether or not the rogue with a passive Perception score of 18 will spot the rune or not.) But you nevertheless retain most of the advantages of using passive Perception scores, because you’re not making a roll for every individual PC (which would be time-consuming and also have a drastic impact on the probability of the check.)

RANDOM SPOTTING PRIORITY

Once the Wisdom (Perception) DC is set, you’ll know which PCs, if any, successfully noticed whatever the target of the check was.

If there are multiple PCs who succeeded on the check, randomly determine which of them noticed the target first.

This is a simple way of systemically spreading the “spotting something” spotlight around, giving different players an opportunity to call attention to a cool tapestry, sneak a gem into their pocket, or determine what the group’s reaction to approaching goblins might be.

Is this “fair” to the PC with the highest passive Perception score? Frankly, yes. Note that they’ll still get spotting priority more often than anyone else in the group, because (a) they’ll participate in more spotting priority checks than other PCs and (b) there will be some checks where they’re the only PC to succeed.

Alternative: If it’s a combat situation — or a potential combat situation — you might use Initiative checks to determine first spotter.

VARIANT: LET PERCEPTION RIDE

An alternative method for passive Perception scores would be to have the group roll Perception checks at the beginning of a delve, raid, or session and then let the result ride as their passive score for the run.

This means that for some sequences the rogue will have the highest passive Perception score and in other sequences it will be the barbarian or the wizard. It will move around the table, creating variable outcomes over time.

VARIANT: TAKE 0

To lessen the importance of passive Perception without completely eliminating it, base passive Perception scores on Take 0 instead of Take 10. In other words, a character’s passive Perception score is simply equal to their Wisdom (Perception) modifier.

Particularly at Tier 1, this will mean that passive Perception may not even succeed at Easy tasks. That’s okay, because in surprise situations you’ll be calling for a rolled Wisdom (Perception) check in these cases. It will also encourage the players to make active Perception checks, engaging with the environment to find stuff instead of just relying on their passive scores to take care of it.

In practice, when using this variant, you’re really just keeping a list of the lowest possible Wisdom (Perception) check possible, so you know the threshold at which it becomes pointless to roll the dice and you should just tell the PCs what they see.

Remember, of course, that this also applies to the NPCs.

Alternative: Base passive Perception on Take 5, so the score is 5 + the character’s modifier. Combined with consistently applying disadvantage for distraction, this will often create a baseline similar to Take 0, but with passive Perception still having a bit more of a meaningful role in the system.

Let’s talk about encounter balance.

A common misconception is that the challenge rating system in D&D is meant to guarantee specific encounter outcomes: The CR = X, therefore the encounter will end with precisely Y resources depleted.

This isn’t really true. Furthermore, I would argue that it’s not possible for any challenge rating system to accomplish this (unless you so thoroughly constrain player choice as to choke out the creative heart of an RPG), because a challenge rating system is inherently limited in the systemic knowledge it can have about a specific encounter.

Factors beyond the scope of 5^th Edition’s challenge rating system, for example, include:

• Players’ tactical skills
• Variance in character builds
• Environment
• Encounter distance
• Stat block synergy (in both PCs and opponents)
• Equipment
• Random dice rolls

(I frequently get static on listing random dice rolls here: “But probability!” Yes, probability exists. But, first, the number of dice rolls in a single fight are often too few for probability to become truly relevant — for the results to conform to the expected value — except over multiple encounters. And, second, the entire point of random dice rolls is to have random outcomes. QED.)

Does this mean that the challenge rating system is pointless?

Not at all. The function of the challenge rating system is to help the DM identify monsters and build encounters that are in the right ballpark. Our first hot take today is that the challenge rating system is actually pretty effective at doing that. And, furthermore, that’s all it needs to do and, arguably, all that it should do.

Despite this, DMs are constantly lured by the siren call of hyper-precision: If we could just account for every single variable, we could guarantee specific outcomes! We wouldn’t even need the players at all! Their choices wouldn’t matter!

(That, by the way, is why this is not actually a desirable goal, even if it was achievable.)

There are several reasons for this.

Partly, it’s the allure of false precision: If we have a Challenge Rating Table, then the designers need to put numbers on the table. And no matter how many times they use words like “maybe” or “might” or “roughly” in describing the function of that table, this can create the expectation that hitting that precise number is important. (In reality, the difference between a 1,600 XP and 1,700 XP encounter is essentially nonexistent.)

The labels applied to different encounter levels also seem prone to misinterpretation. I find this varies depending on the methodology used for the label. In the case of 5^th Edition D&D, the designers have generally chosen a label which describes the worst case scenario. For example, a “Deadly” encounter doesn’t mean “this encounter is likely to result in a TPK.” It actually means that there’s a risk you’ll see at least one PC making death saving throws. (You can think of the possible outcomes of an encounter as being mapped to a bell curve: The outcome of an 8^th-level encounter might, in actual practice, be the average result of anything from a 4^th-level encounter to a 12^th-level encounter. The 5^th Edition label is generally describing a result somewhere a little off to the right side of the bell curve.)

But the final factor is linear campaigns.

THE PROBLEM WITH LINEAR CAMPAIGNS

I’m occasionally accused of hating linear campaigns. This is not the case. I dislike predetermined plots, but that’s not the same thing. I’ve actually talked in the past about how to design linear campaigns, and in So You Want To Be a Game Master I actually have several chapters and adventure recipes for creating linear scenarios.

(A linear scenario is also not the same thing as a railroad. It’s accurate to say that I loathe railroads, and everything I talk about here is probably ten times more true if you’re railroading your players.)

There are, however, consequences for using a linear structure. (Just as there is for using any structure.) This is particularly true if you only use linear structures, which can be the unfortunate case for many DMs who don’t have alternative scenario structures in their repertoire.

A linear scenario inherently means that you, as the DM, are preparing a specific sequence of experiences/scenes/encounters/whatever you want to call them. The players will experience A, then they will experience B, then they will experience C, and so forth.

A consequence of this style of prep, therefore, is that the DM is solely responsible for what the PCs will be doing. This creates an enormous pressure on the DM, because you’d better get it right: You’d better get the spotlight balance right and make sure that every single PC has an equal chance to shine, because otherwise you’re making it difficult or impossible for one of the players to participate. And you’d better get the combat balance right, because forcing the players into fights they can’t win is a dick move.

So the DM will, naturally, spend more effort carefully crafting each encounter to make sure it works. Ironically, the more specific their prep becomes for each situation, the more weight is placed on their shoulders to make sure they get it right. This can quickly decay into a vicious cycle, with the DM pouring more and more effort into every single encounter in order to meet ever-rising expectations. The result is often My Precious Encounters™, in which every encounter is lovingly crafted, carefully balanced, painstakingly pre-constructed, and utterly indispensable (because you’ve spent so much time “perfecting” it).

… and then the challenge rating system isn’t hyper-precise and the players mop up the whole thing with a couple of quick spells?!

This is an outrage!

I guess we’ll just need to lock down more choices, get out the shackles, and try even harder next time guarantee the encounter works exactly as we predetermined it should.

NON-LINEAR BALANCE

Some of you reading this may be thinking, “Okay… but what’s the alternative?”

And when I say that the alternative is non-linear scenarios, your gut reaction is likely to be, “You mean design even more encounters? And the players might not even encounter some of them? I can’t do that! Do you know how much work I put into these encounters?!”

In truth, however, non-linear design is a completely different paradigm: The players are now able, to at least some extent, choose the experiences they’re going to have. And because the players now have responsibility for what they do and how they do it, that weight is lifted from the DM’s shoulders.

Looking at just the issue of combat balance, for example, if the PCs run into an encounter in a linear adventure that they can’t defeat, that’s a disaster! They can’t move forward unless they defeat the encounter, and they can’t defeat it, so they’re completely stuck. It’s as if they lived on an island and the only bridge to the mainland was closed for construction.

In a non-linear scenario or campaign, on the other hand, if the PCs run into an encounter they can’t defeat (or which they just think they can’t defeat or which doesn’t look fun to them), then they can just change direction and find a route around that encounter. Or, alternatively, go and do something else until they level up, gain magic items, make allies, or otherwise become powerful enough to take out the challenge that was previously thwarting them.

You can see an analogous set of paradigms in video game RPGs: Some will allow players to grind XP, allowing them to dial in the mechanical difficulty they’re comfortable dealing with at their level of skill. Other CRPGs will level up the world around the PCs or limit the total amount of XP they can earn. The former games can appeal to a broader range of skill levels and the designers have a lot more leeway or flexibility in how they design the challenges in the game. The latter games have a lot less flexibility, and players can end up completely stuck (due to lack of skill, a mistake in their character build, disability, or any number of factors).

LINEAR BALANCE WITH MILESTONES

Okay, but you want to run a linear adventure. Maybe that’s the best structure for the campaign you’ve got planned. Maybe you’ve picked up a published adventure that uses a linear structure and it’s just not working: It’s too easy or it’s too hard, and you want it just right.

Fortunately, there’s an incredibly powerful tool you can use for balancing linear campaigns: Milestone leveling.

The trick is that you just need to ditch the idea of hardcoding the level ups to specific beats in the campaign. Instead, after each scenario, do an assessment of how your encounter balance is working in actual practice:

Are the players cruising through stuff? Increase the difficulty of encounters. If you’ve been designing 6th-level encounters, bump them up to 7^th-level encounters. (You can also change the balance of Easy/Medium/Hard/Deadly encounters you’re using, or do half-step bumps in XP budgets between levels.)

Are the players feeling challenged? You’re in the sweet spot. You can hold in that sweet spot for X sessions, with the number X being adjusted to your personal taste. Then you can start increasing the difficulty by steps again until…

Are things getting really tough for the PCs? Level them up (without immediately shifting encounter difficulty) and then assess.

One thing to be aware of is that this doesn’t work great for 1^st-level characters, which are very fragile (and kind of need special treatment when it comes to encounter building in general).

Another thing to keep in mind is that you need to miss very low and for a very long time for “too easy” to ruin your campaign; you only have to miss once for “too hard” to TPK the group. So, when in doubt, you’re generally better off aiming low and then adjusting up.

You’ll also likely discover that sometimes PCs will level up, feel like they’re in the sweet spot, and then suddenly everything gets easier and they’re cruising through encounters that are too easy. What’s likely happened is that the players have figured out how their new abilities work (and, importantly, work together), allowing them to perfect their tactics.

You can see the opposite effect happen if the PCs have been fighting one type of monsters for awhile, but then the campaign shifts and they’re suddenly fighting completely different monsters. Experienced difficulty may momentarily spike until they get a feel for the new creatures.

It’s also not a bad idea to check in with the players periodically and see how they’re feeling about the difficulty level in the campaign. They won’t always be right, but neither will you, so comparing notes can help you find the sweet spot for your group.

“Hey! Isn’t that actually Level Advancement Without XP?” Sorry, folks. The ship sailed on this one back in 2014 when every single official adventure started referring to “you pick events in the campaign when the characters level up” as milestone XP. “Milestone” is just too convenient a term for the form of level advancement best suited to these linear adventures. If you have any complaints about this, please address them to Wizards of the Coast.

LINEAR BALANCE WITHOUT MILESTONES

“But I don’t want to use milestone XP! I want to give XP for combat!”

… you just want to make things difficult, don’t you?

That’s okay. Once you understand the principles described above, you can accomplish the same effect with combat/challenge-based XP, it will just be a little more obfuscated.

Specifically, with XP awards, the PCs will be gaining levels at a certain pace. If they’re cruising through encounters, you just need to increase the difficulty of the encounters they’re facing at a faster pace than the pace they’re leveling at. (So in the time they’ve gone from 6^th to 7^th level with everything feeling too easy, the encounters you’re building will have gone from 6^th level to 8^th level or maybe even 9^th level. Or, conversely, if the encounters have been too tough for them, you might hold the encounter design at 6^th level even though they’ve leveled up to 7^th.)

In other words, it’s the same process of dialing in: It’s just made slightly more complicated by the PCs being a moving target.

OTHER FAQs

“Doesn’t this mean that my 7^th-level PCs could end up facing, I dunno, 11^th-level encounters?”

Quite possibly. Or your specific group of 7^th-level PCs might be better served by 5^th-level encounters. If it makes you feel better, even by-the-book 11^th-level Medium encounters are actually easier than 7^th-level Deadly encounters, so you’ve probably already been doing this.

More importantly, these are just arbitrary numbers. The important thing is that you and your players are having fun: If your players are really good at tactical planning or they’ve managed to get their hands on an unexpectedly powerful magical artifact, that can easily mean that they’re capable of punching above their by-the-book weight-class.

And you know what? That sounds fun to me!

“I’m running a published adventure. How do I ‘increase the difficulty’? Do I need to rebuild the encounters?”

Instead of adjusting encounter difficulty, just skip the next milestone level suggested by the scenario. You can see a similar technique in Random D&D Tip: Adjusting Encounters by Party Size.

“Couldn’t I use these same principles when designing non-linear scenarios or campaigns?”

Absolutely!

For scenarios, you’re generally targeting a certain difficulty in your encounter design regardless of whether it’s a linear or non-linear scenario. This technique is about dialing in what your current target should be in the challenge rating system, so it works just as well either way.

For a non-linear campaigns, you want to avoid the potential pitfall of leveling up the campaign world. So if you’ve got a structure like a megadungeon or hexcrawl, where the players can already dial in their preferred difficulty level, this technique probably isn’t going to be particularly useful. But it can find application in some node-based campaigns and freeform sandboxes.

FURTHER READING
Revisiting Encounter Design
The Many Types of Balance
Fetishizing Balance
The Death of the Wandering Monster
Adversary Rosters

Whether you’re talking about Jaroo Ashtaff, the Level 7 Druid, from AD&D, a Goblin Wizard 14 from 3^rd Edition, or a 5^th Edition Archmage, the trickiest bit of creating an NPC spellcaster is filling in their spell list.

For example, let’s take a closer look at the 5E Archmage’s spellcasting capability:

Cantrips (5, at will):

1^st Level (4 slots):

2^nd Level (3 slots):

3^rd Level (3 slots):

4^th Level (3 slots):

5^th Level (3 slots):

6^th Level (1 slot):

7^th Level (1 slot):

8^th Level (1 slot):

9^th Level (1 slot):

Now, obviously, in this case we can actually use the default spells provided in the Archmage stat block. But wouldn’t it get a little boring — in a game teeming with hundreds or thousands of amazing spell options — for every Archmage to cast the exact same set of spells?

And so here we are, picking out twenty-five spells one by one.

It’s laborious.

And particularly daunting if you’re creating a spellcaster on the fly in the middle of a session: The PCs zigged in an unexpected direction or zagged by unexpectedly picking a fight. Quick! Pick a dozen (or two dozen!) spells in the time it takes the players to roll initiative!

THE BLANK TEMPLATE

If you take a second peek at the blank Archmage template above, you’ll see the technique I use when this situation comes up at the table.

(Which, of course, it inevitably does.)

Rather than listing the spellcaster’s spells, I just list their daily capacity.

Then I’ll grab a copy of the Player’s Handbook (or its local equivalent; similar techniques work in a wide variety of games) and flip it open to the appropriate spell list.

When it comes time for the NPC spellcaster to cast a spell, I’ll simply choose whatever spell feels appropriate and add it to the previously blank template. Over time, the template fills in.

The drawback to this technique is that it requires a bit more system mastery, since you’ve just multiplied their spell selection each round from a list with a handful spells on it to literally every spell in the book. But it’s not like you need to actually memorize every spell in the book: with just a little familiarity, you can rely on the spells you’re familiar with, grab anything else that looks particularly cool or appropriate as the need arises, and slowly expand your repertoire.

Plus your Player’s Handbook is already flipped open to the right page, so thumbing over to the description of a spell you’re not completely familiar with should be fairly easy.

CONSTRAINING CHOICE

Another effect of this technique, obviously, is that if you play it for maximum mechanical advantage your spellcasters are significantly more powerful than they were before! After all, “they” get to pick any spell they want at the very moment they need it! That’s not fair!

First, good sir or ma’am: ARE YOU A GAME MASTER OR AREN’T YOU?

Just… don’t do that. Ask yourself, “Does it make sense for them to have this spell?” And, if it doesn’t, don’t use it. If you don’t think you can answer that question truthfully, then flip a coin or roll a die when in doubt.

If you want a different form of constraint, consider defining a spell “theme” for the NPC caster: Maybe they’re a fire mage or a defense specialist or a summoner. Limit their spell selections to this theme: In addition to making the encounter more flavorful, it will place a reasonable limit on you unlimited spell selection and maybe even push you out of your comfort zone, encouraging you to experiment with new spells you haven’t gotten comfortable with yet.

Another constraint might be eliminating 25% or even 50% of their spell slots. For example, we might take our Archmage template and do this:

Cantrips (5, at will):

1^st Level (4 slots): X

2^nd Level (3 slots): X X

3^rd Level (3 slots): X

4^th Level (3 slots): X X

5^th Level (3 slots): X

6^th Level (1 slot):

7^th Level (1 slot): X

8^th Level (1 slot):

9^th Level (1 slot): X

With each X representing a spell they’ve already used today or, alternatively, a spell they’ve prepared that isn’t relevant to the current encounter (depending on edition and spellcasting class). This limited capacity counteracts, to at least some extent, the greater flexibility of their spell selection. Plus, it probably just makes sense more often than not: The NPC was probably just going about their day, casting their spells the way they normally do. It’s actually pretty unrealistic when every NPC spellcaster shows up with their full daily allotment of casting ready to drop on a single encounter.

SAVE YOUR SPELL LISTS

Whether you’re prepping spell lists in your adventure notes or jotting them down desperately in the middle of the session, save the list. Give it a label like “Fire Mage” or “Death By Lightning.” Copy it into a repository or drop it into a file folder.

Over time you’ll build up a valuable trove of spell lists. Eventually, you won’t be left scrambling when the players zig-zag: You’ll be able to grab the most appropriate list, give it a couple of twists, and run with it.

The encounter creation guidelines in the Dungeon Master’s Guide and Xanathar’s Guide to Everything are both based on the idea that you know how many PCs are in your group. Then you do a table lookup, do a little math, and – presto! – you have a budget to spend on your encounter, expressed as either an XP amount or a number of creatures of a particular challenge rating.

But what if you’re using a published adventure with a party that’s a different size than the one recommended? For example, what if you’re running Curse of Strahd (“for four to six players characters”) but your group only has three PCs?

Going strictly by the book, you would need to deconstruct the encounters in the book to calculate the original XP budget, determine what difficulty the encounter was designed for (Easy/Medium/Hard/Deadly), calculate the correct XP budget for your PCs, and then rebuild the encounter using the new XP budget. (Which may or may not be possible with the original creature(s) used in the encounter.)

Here’s the tip: It’s a lot easier to adjust the level at which your PCs play the adventure than it is to redesign every single encounter.

• For Tier 1 & Tier 2 characters, increase their level by +1 for each “missing” PC from the party.
• For Tier 3 & Tier 4 characters, increase their level by +2 for each missing PC.

Or vice versa for additional PCs.

To put that another way, if a published adventure’s recommended level is X, then at Tier 1 & 2 use it for PCs who are level X + 1 per fewer PC and Tier 3 & 4 use it for PCs who are level X + 2 per fewer PC.

So if you’re running Dragon Heist, which is recommended for five PCs, with a three-person group, you’d either want to start them out as 3^rd level characters (instead of 1^st level characters) or run a prequel adventure or two to level them up to 3^rd level before using the published Dragon Heist campaign.

BONUS TIP #1

Challenge ratings are not that precise. They’re not designed to be a guarantee (nor can they be). They are a very rough approximation of “on average.”

Some “balanced” encounters will be easy. Some will turn out to be surprisingly difficult.

That’s okay. No game, no adventure, no session is about a single encounter.

The flip-side of this is that you don’t need to worry too much about getting an encounter exactly right. It’ll mostly get washed out in the general noise – the imprecision of the system, encounters being designed over a spread of challenge levels, situational conditions of the battlefield, and so forth.

This is also why Wizards of the Coast can release adventures “for four to six player characters” of a given level. Such adventures are designed for five PCs. They’ll be a little bit harder for four PCs and a little easier for six PCs, but it’ll be just fine.

BONUS TIP #2

In terms of strict math, the rule of thumb described here breaks down for very large groups of 9+ PCs. But there are more significant balancing issues based on action economy that make creating and running encounters for such large groups more of a special snowflake in any case. (Short version: Ten PCs, with all their attacks and all their special abilities, are able to wreak an amount of havoc that is out of linear proportion to a group of four. But, conversely, you can’t just use more powerful creatures, particularly at lower levels, because the monsters can one-shot individual PCs before they go down.)

For groups of 8 PCs, rather than running higher-level adventures, you can get pretty good mileage out of taking an adventure designed for five PCs and just doubling the number of creatures in the encounter.

For groups of 9+, adjust the encounter based on the difference between the PCs’ group size and a group size of eight, and then double the number of creatures. (This breaks down somewhere in the teens, but I would… uh… strongly recommend not running groups that large.)

This can create some weird narrative challenges if the encounter was, for example, with a solo boss or the like. But those are the types of encounters which really don’t work with large groups in any case, so you’ll just need to give them a little more TLC.

BONUS TIP #3

Whatever approach you’re taking to encounters — prebuilt, custom built, or otherwise — remember that you can always dial it in over time: If the encounters you’re building are too hard, trim the XP budgets in the future (no matter what the by-the-book math says). If you’re running a published adventure and the PCs are steamrolling the opposition, hold back on leveling them up. Or, vice versa, level them up faster if they’re struggling.

As you’re getting a feel for things, keep in mind that you have to miss by A LOT and for a very long time for “too easy” to not be fun.

You only have to miss once for “too hard” to be a campaign-ending TPK.

So erring on the side of easy is recommended. You can dial it up from there.