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D&D 5E So, I figured out why 5e's encounter building is broken(and how to fix it)


5e's encounter building in infamously messy, with some fights being marked as "even" being remarkably easier, and some fights listed as "Hard" not feeling like it, this make it hard to challenge players, and makes 5e's encounter design feel messy. (Its why you should play Level Up! 5e because its better at dealing with this).

But i've actually found out why.

First lets go into the whole Daily XP Budget/Adventuring day, and what that means.

You see the XP budget, is actually how this game is balanced, you see XP isn't just an arbitrary number for progress, its actually an estimate of the "power level" of a monster, it is quite literally a estimate of how much damage a monster can do before going down, and the Daily XP Budget? Is actually an estimate of how much health/damage players can actually have in adventuring day. I went into this more in this post if you wanna read about it

So when you are making an encounter, and looking at the XP Budget, its actually just estimating how much damage a monster can do to their total collective HP/HD pool before croaking. Thats all its doing. There is one thing about this though, the total XP Budget, is also under the assumption that at least one per day, the party will short rest, and use most of their hit dice to regain all of their health, if they do not do this, their Daily XP Budget is halved, this is important. (The reason the game says two Short rest per day, is because they assume that when your at around half health you will short rest, so you will on, average do this twice.)

(Fun Fact: Casters total Health/Damage XP budget mostly comes from their spells, without them they are way behind the curve, everytime a caster casts a spell the total XP from it drops because they are losing their defensive option/damage option.)

Now that last bit is important, because half of the XP Budget, is actually how encounter balancing is done, The "Easy", "Medium", etc, encounter difficulties are just how much damage a monster can do to that half XP budget, aka how much damage they can do before they are forced to short rest.

Easy is about 10-15%, Medium is about 25-30%, Hard is about 40%-45%, and Deadly is about 60-70%.

You can go check yourselves, but this basically is also the expected amount of damage a monster can do to the party, in a single encounter, knowing this alone you can basically make encounters about as flexible as you want, just simply stay under 90% of half of the XP Budget.

This is also where the 6-8 adventuring day comes from, because this means you can only take 6-8 encounters before literally not having enough health/HD) to continue using medium-hard encounters. That is all the Adventuring day means, its just talking about this, no other resources.


Now this is all fine and sound, and it actually works really well, but there is one fundamental issue with encounter building, one that broke it.

In the DMG, there is guidance on how to deal with multiple monsters, it starts at a 1x modifier and goes up for the multitudes of monsters you add starting at one monster. This seems sound, but it has one fundamental error, that actually breaks the encounter building of the game.

It does not account for action economy, the game tells you to adjust the XP modifier of the monster for each additional monster added to the encounter, but...doesnt account for your party size, and how to adjust it the monster's XP if its outnumbered.

Action economy is king in 5e, because of bounded accuracy, higher level monsters cannot just stat stick their way to tanking everything, they can reasonably be affected/hit by a bigger party, the actual math of the multipliers in the DMG are actually straight up broken and nonsense. A monster is worth less XP in the budget, because since they are outnumbered and out-actioned, they will due to this, likely take significantly more damage before they can act, meaning they less likely chance of doing their average damage expectation in the encounter before dying. This means when outnumbered monsters XP Budget is lowered in the multiplier, The multipliers in the DMG do not go into this or account for this at all. And instead gives you a completely broken methodology that actually does not work, its all complete nonsense, it was a rush job. Action Economy matters for the monsters too, because even if they can do the damage in stats, if they are outnumbered the odds of them having enough turns to do so is lessened. (This does not apply to legendary monsters since legendary actions actually lets them match the action economy.)

This fundamentally breaks 5e's encounter building, this poor multiplier guidelines in the DMG leads to encounters being easier, because its giving actively bad guidance on how to account for monster action economy, Even accounting for an average party of 4, Monsters drop a whole tier of difficulty if accounted for, Medium becomes Easy, Hard becomes Medium.

This is a Critical error in guidance in the DMG's part. And Its why 5e's encounter balancing is broken

Also note that The games current damage expectations from each encounter also lend itself to being easier, because they turned their old Easy difficulty from the playtest to the current medium.

So an already easier-made game, due to this error, is even easier and makes encounter building less accurate. Luckily this is easy to fix


The first method simply just accounts for your party size in the XP value of an encounter properly(the DMG has a method of doing so but it is just as broken as the rest of it since it only matters if you have a notably bigger party, but not account for the advantage of just a party of 4). And here is a simply flx made by 5e brewer u/badooga1 here credit to him, he figured this out years ago. And beat me too making a post about this, but i feel im going for a more detailed approach here.

The total XP multiplier is equal to the number of monsters (or 3, whichever is higher) ÷ the number of characters in the party.
(The minimum of 3 is meant to represent boss fights that have legendary and possibly mythic actions. Furthermore, contributions from very weak monsters to this calculation can be excluded or reduced as appropriate.)
This basically adjusts the issues and gives you more balanced encounters in general that actually account for the action economy in total when building them.
Making encounter building far more accurate.

The other major issue is how the encounter guidelines for a "Medium" or Easy encounter have been toned back to make it far too easy to fit the difficulty name.

So a simple adjustment to get encounters that actually fit with the names.

Halve the daily xp budget.
And just add monsters while trying to stay under 90% that. That is the absolute maximum they can take before they will certainly die without extra resources.
25% of it is easy, 50% of it is medium., 75% of it is Tough. 80-90% is Deadly.
Try to avoid 100% or over, without some serious resources to mitigate this, your party would. certainly, die.They can only handle 100% before needing to short rest, and 200% total daily.
This will get you more challenging and accurate to name encounters in the system, and allow you to flexibly build encounters easily.

Thats all I hope this helps, and you run funner games.

TL/DR: The DMG guidelines for dealing with action economy against monsters is actually broken and bad, and not properly accounted for making encounters actually a whole difficulty easier, and making encounter balancing way harder.
Just make the encounter XP multiplier is equal to 3 ÷ the number of characters in the party, if its only 1 or 2 monsters. If its has 3 or more monsters, make the multiplier is equal to the number of monsters ÷ the number of characters in the party. And calculating the XP in the end, you get the actual how much that monster is worth in terms of power, for encounter building.

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The High Aldwin
I've never found much issue with the system in the DMG, with one caveat: Solo Bosses have maximum HP.

9 times out of 10 if the encounter ends up being easier or harder, it was due to good/poor strategy, dice rolls, etc. than the encounter, itself. 🤷‍♂️

I've never found much issue with the system in the DMG, with one caveat: Solo Bosses have maximum HP.

Solos should really be Legendary (if they're not already, that's an easy slap on) and (going by Encounter design charts) should generally have a CR around 5 higher than the average party level.

5 x 7th level PCs have a 'Hard' encounter budget of 5500 to 8500xp.

Meaning a CR 12 is an appropriate challenge for that party (and it only takes up 1/3 of that days XP budget, so they could reasonably be expected to deal with 3 such encounters in a single long rest cycle, with a short rest after each encounter).

For example, take a CR 11 Horned devil, remove a Fork attack, then give it 2 Legendary saves, and 2 Legendary actions (Fork, Hurl flame and 'moves half speed without provoking AoO) and bump its HP up to 200 (and its CR to 12) and you have a Hard solo encounter for 5 x 7th level PCs.


The DMG mulpliers are reasonable if you assume PCs are decent at AOE.

The basic model of a monster's power is (effective HP)*(effective damage output), where effective takes into account accuracy.

If we assume monsters fight PCs "near" their CR, you can convert accuracy and defence to a simple multiplier on HP and DPR. Once you've done this, if you imagine a "fake party" with roughly expected accuracy making 1 HP damage per turn attacks who in turn has infinite HP, the monster power I mention above gives you how much damage the monster does before it dies.

As you scale up this fake party damage to X HP per turn, the damage the fake party takes is ... roughly divided by X.

(For regeneration cases you have to be a bit less abstract).

The XP value of a monster is pretty close to this product; I think there is a factor of 3ish?

For multiple monsters when you add up their XP, you model the congo-line situation. Imagine the fake party fighting monster 1, then monster 2, then monster 3. This is "add up the XP of the monsters".

Now, as you can imagine, monsters don't fight in congo lines usually. If we assume all of the monsters are roughly equal and they all swarm at once, when 3 monsters attack the fake party will take 6x one monster's damage, not 3x. If 4 monsters attack, it is 10x not 4x. And if 5 monsters attack, 15x instead of 5x.

The number here is called a triangular number -- it is 1+2+3+4+5+6+... etc. It isn't quite the square, but it grows faster than linearly.

If you divide the triangular number by the linear number, you get 1, 1.5, 2, 2.5, 3, 3.5, 4 -- you get (N+1)/2.

So if we assume foes swarm the party, and the party focus fires down one monster at a time, the proper XP value for N monsters is N*1 monster * (N+1)/2.

This is lower than the DMG, as you have observed. But there are two assumptions here.

First, the party does perfect focus fire and has no AOE.
Second, the monsters can engage the party with perfect efficiency.

When you have many foes, often the foes get in each others way. Second, AOE massively increases the capabilities of the party against large numbers of foes.

Between the two of them, we get closer to N^0.4 as the "encounter size multiplier" instead of the naive "N+1".

None of this cares about action economy. It cares about (a) the expectation that you'll be eliminating monsters, or (b) you'll be using AOEs to deal efficiently with multiple monsters.

Finally, we can model what happens if the fake party spreads damage out. Then all N of the monsters deal damage each round, and they last N times longer than a single monster. This corresponds to a multiplier of N, instead of (N+1)/2.


Your model, where you scale team monster's XP by its side size, reflects players not doing any AOE or any focus fire at all.


On the other hand, the model assumes PCs are not being eliminated. That between healing and tactics and abilities, team PC avoids being taken out, so their damage flux doesn't drop.

This is why the fake party has one basket of HP and steady damage output.

A real party also does spike damage. This can help eliminate foes when there are more than 1 of them early in the fight, which has high value, and another reason why N or (N+1)/2 is not a great model.

A smart party will burn more resources in the earlier, more dangerous parts of a fight with N foes than they will at the tail end. Meanwhile, the simple model I described had flat damage output.


It took me half-a-dozen sessions to realise that the default guidelines were pitched at one difficulty level too low for my players. When you also realise that the encounter guidelines are a starting point for encounter design, not an ending point (the game has too many unknowables for any mathematical framework to work for everyone), you're golden.


It took me half-a-dozen sessions to realise that the default guidelines were pitched at one difficulty level too low for my players. When you also realise that the encounter guidelines are a starting point for encounter design, not an ending point (the game has too many unknowables for any mathematical framework to work for everyone), you're golden.
Yes, I do think this understanding is crucial. However, I also wish the DMG gave more guidance on this point (adjust encounter assumptions for part size, equipment, ability, and how they play). I don't particularly need it, but I think it would be good for newer DMs.


While I've never been that interested in the encounter guidelines (my first campaign averaged Deadly x2), but I've found the quick matchup in Xanthars to be excellent. I've been using it during the 1D&D playtest, and I've had little issue.


I use an alternative I got on this forum years ago that completely ignores the numbers multiplier. Still works reasonably well. I may try the method(s) mentioned above, but I just plug in numbers and I'm good to go.

But the main thing? No calculation will ever be 100% accurate. There will always be variation from group to group, along with types of creatures, how many encounters the group has had prior, environmental factors. Just as important? How effective is the group at combat and, of course, how effectively the DM runs the monsters. I've run for two different groups of the same level with the same options at the same time and one group was simply able to handle far more than the other.

I've adjusted my expectations for my group based on experience and it works pretty much as expected at least 80% of the time. Sometimes the dice are hot, sometimes I set up the environment to be a little too advantageous to the enemy or optimal tactics would simply be boring. So nothing is perfect, but you can get pretty close.

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