How deadly is the Monster Manual?

A DM-friend of mine once said: ‘I love it when the players level up – it means I get to use the fun part of the Monster Manual.

This got me thinking. As players climb the levels, how much of the Monster Manual can – and should – the DM make use of?

Ultimately this boils down to encounter difficulty. According to the Dungeon Master’s Guide (pp 82–83), some monsters will be too powerful for characters of a particular level. A party of four 12th-level characters should be able to take on an iron golem (CR 16), but the same encounter could be ‘deadly’ for a party of one level lower. I decided to examine what percentage of the Monster Manual was ‘available’ (ie, not deadly) at various levels of play. Scroll down for the findings.

Big disclaimer here: 5th edition encounter design is not a science. In fact, it has all sorts of problems, and it is probably one of the areas of the core rules most in need of revision. I started listing specific reasons why, but honestly, it’s an article in its own right.

Still: despite this, I thought it would be fun to run the numbers and see how much of the Monster Manual your party can survive.

  • There are 450 monsters in the Monster Manual. This includes the animals in Appendix A, the NPCs in Appendix B, and all the different variants along the way (eg, the different size categories for dragons).
  • Many of these monsters are not necessarily adversaries. 53 are of good alignment, and 253 are ‘not evil’.
  • Monsters range in Challenge Rating from 0 (a frog) to 30 (the tarrasque). According to the DMG method, the tarrasque is essentially a Borderlands-style ‘raid boss’: it will be ‘deadly’ for most 20th-level parties, and you will need at least seven characters to tip the balance in the party’s favour. (Having run the tarrasque a couple of times at my table, this doesn’t fit with my experiences.)
  • I am going to assume a party of four adventurers. Bigger groups can take on bigger enemies whereas smaller groups will struggle against monsters of higher challenge ratings.

Putting it all together

This is what I found.

Party levelMax CRNumber of monstersPercentage of Monster Manual
1st117439%
2nd327160%
3rd429365%
4th532873%
5th837082%
6th938185%
7th1038986%
8th1139888%
9th1240189%
10th1341091%
11th1542093%
12th1642594%
13th1843396%
14th1943496%
15th2043797%
16th2043797%
17th2144198%
18th2144198%
19th2244398%
20th2344799%

Some interesting patterns:

  • Even at 1st level, more than one-third of the Monster Manual is ‘not deadly’.
  • More than half the Monster Manual is available by 2nd level. For many groups, that’s a session of play.
  • In fact, the biggest jump in ‘availability’ is from 1st to 2nd level.
  • By Tier 2, three-quarters of the Monster Manual is available. By Tier 3, 90 percent of monsters are ‘not deadly’.

What are the implications of this?

First of all, it shows that the Monster Manual is excellent value for money! You don’t need to play for months on end to ‘unlock’ the most powerful monsters. Most of them are available for 2nd level onwards.

Secondly, we shouldn’t worry too much when we are picking individual monsters for our players to face. Once you’re out of low levels, most of the Monster Manual is fair game.

Finally, it shows that truly challenging high-level monsters are hard to come by. Only 17 monsters in the Monster Manual are CR 20 or higher, and seven of these are good-aligned. There are another 21 in Mordenkainen’s Tome of Foes and 25 more in Fizban’s Treasury of Dragons. If you’re running a high-level campaign, raid these books.

A corollary: trivial encounters

As a follow-up, I thought I would flip this round. When do the creatures in the Monster Manual become too easy?

The DMG only lists four encounter difficulties – easy, medium, hard, and deadly – but D&D Beyond lists a fifth: trivial. According to D&D Beyond, a trivial encounter is ‘even easier than easy [. . .] You’ve technically added monsters to the encounter, but a hearty sneeze from your party might just about end the fight.’

Of course, even a low-level enemy can be challenging in numbers, so in theory, we can keep using goblins all the way up to 20th level. In practice, that’s not quite true. A 20th-level party could cut through 50 goblins and still find the encounter trivial. For the sake of this article, then, I am going to need an arbitrary cut-off point. According to Sly Flourish, the mechanics of D&D combat generally presume the characters will face somewhere ‘between three and twelve bad guys’ in any given battle, so let’s go with twelve. At what point do twelve bad guys become trivial?

Let’s take the table above and add a new column: ‘min CR’. These are monsters who, even in groups of twelve, are still a trivial encounter for the party. This doesn’t kick in until 4th level, when CR 0 opponents start to become truly trivial.

Party levelMin CRMax CRNumber of monstersPercentage of Monster Manual
1st117439%
2nd327160%
3rd429365%
4th0529766%
5th831670%
6th932773%
7th10335 74%
8th11344 76%
9th¼1230367%
10th¼1331269%
11th¼15322 72%
12th½16288 64%
13th½1829666%
14th½19297 66%
15th½20300 67%
16th½20300 67%
17th12126759%
18th121267 59%
19th122269 60%
20th123273 61%

What are the implications now?

Firstly, low-level monsters are useful for a surprisingly long time. Even after 100 hours of play, a bunch of orcs or hobgoblins will not be a trivial encounter.

Secondly – again – the Monster Manual is pretty good value for money! From 2nd level onwards, there is always at least 59 percent of the Monster Manual available for encounters.

Finally, the sweet spot is Tier 2. From 5th to 10th level, about 72 percent of the Monster Manual is available (on average). That said, there is a pleasingly even spread from 2nd to 20th level, and no noticeable dearth in the numbers apart from 1st level.

Of course, trivial and deadly encounters both have their place, whether it’s Tier 4 heroes wading through an army of gnolls or Tier 1 adventurers coming face to face with a great red wyrm. Don’t worry too much about your encounters. Choose what makes sense for your story.

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