How to Create a D&D Monster for Fifth Edition in 15 Minutes or Less

DM Dave4 CommentsPosted in How to Guides

Occasionally, I get folks on Instagram and Facebook asking me how to create a D&D monster for Fifth Edition. Of course, the Dungeon Master’s Guide outlines how to do just that on pages 273 – 283.

But for some that can be a little overwhelming. And there are lots of little rules that are easy to miss.

So, I thought I’d take the opportunity to go over how to create a D&D monster for Fifth Edition. After all, I create, on average, probably 10-15 new monsters each week.

Below is a look into my monster design process for Dungeons & Dragons Fifth Edition:

For a long time now, this has been one of my most popular articles. Recently, I got off my lazy butt and finally decided to create a PDF for this. You can get it on my Patreon. That way, you can download it and read it on your own time. Plus you get another 90+ PDFs with new ones every day.

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Step #1 – Come up with the concept.

The first thing I do when I create new monsters for Dungeons & Dragons Fifth Edition is think about what I want the monster to do and what its purpose not only in the game is, but the fantasy world itself.

Is the monster a minion? Or is it a big bad evil guy/girl (BBEG)? Do I want the monster to be memorable, or do I want the monster to be sort of an “asshole monster”, the type my players will never forget?

Once I have the basic concept down, I do a little shopping.

In this example, I want to create a two-headed goblin. Why? Because I love goblins! Plus, this artwork from MTG artist Mike Burns is just too funny!

Step #2 – Figure out the “base monster.”

Once I have the concept, I then turn to the book I consider the “Rosetta Stone” of Dungeons & Dragons Fifth Edition: the Monster Manual. When learning how to create a D&D monster, this is your best resource. In fact, it’s pretty rare that I have to reference any other book. With nearly 500 monsters all with tons of features, actions, and options, there’s bound to be something in there that comes close to matching what I conceptualized in Step #1.

Let’s take a look at our two-headed goblin concept.

First off, I know that I’d want to look at the goblin stat block on page 165 – 166 of the Monster Manual. This will help me figure out the characteristics that all goblins should have in common.

From this stat block (and the accompanying Goblin Boss stat block) we learn that both goblins share the following features:

They’re small humanoids.
And they have the goblinoid tag.
Their alignment is neutral evil.
Basic goblin “warriors” have 2 hit dice, while elites have 6.
Goblins have below average Strength, Wisdom, and Charisma; above-average Dexterity; and average Constitution and Intelligence. The elite goblins are slightly stronger and charismatic.
They are naturally stealthy, getting double their proficiency bonus to Dexterity (Stealth) checks.
Thanks to darkvision, goblins can see in the dark up to 60 ft.
Goblins speak both Common and Goblin.
All goblins seemingly have the Nimble Escape feature which allows them to take Disengage or Hide as a bonus action on each of its turns.
The elite goblins get Multiattack and the Redirect Attack reaction which allows it to swap places with another goblin (whaddajerk).

Knowing all this, we can start customizing our goblin with secondary characteristics.

Step #3 – Shop secondary characteristics

Next, I want to find secondary characteristics that fit the concept. The best way to do this is to find a creature that has options that are similar to what we’re looking for, but not enough other motifs to warrant it being the base creature.

We know a lot about goblins now, but we don’t know much about two-headed goblins. Fortunately, there are a couple of different monsters in the Monster Manual that has more than one head.

First, we have the obvious choice, the ettin (page 132). The ettin’s two heads gives it some interesting features, some obvious and some subtle. The obvious features are its Two Heads and Wakeful features. The subtle feature is its expertise in Perception (double proficiency bonus).

Next, there are death dogs (page 321). Death dogs also have double the proficiency bonus in Perception as well as the Two-Headed feature. Note that the wording of the feature’s name is different than the ettins although it’s exactly the same. Tsk, tsk, WotC copywriters.

Finally, we have the chimera (page 39). Like the ettin and death dog, the chimera has double the proficiency bonus. However, it doesn’t have a special feature related to its multi-headed nature.

There is one more subtle feature that all these creatures have in common: multiattack! The chimera can attack once with each of its heads (or parts, if you count the lion head’s claw attack as a “head”), the ettin makes two attacks with each of its weapons, and the death dog makes two bite attacks. This makes me think that having more than one head makes the creatures better at multiple attacks.

Observing all this, I’m going to give the goblin Multiattack, Two Heads, and double its Perception proficiency. Goblins are inherently lazy, so I can’t imagine them being “wakeful”, even with two heads.

Step #4 – Put it all together.

The next step on how to make a D&D monster involves putting it all together. Since we have the base creature decided and its secondary characteristics picked out, we can start creating its rough stat block.

Here’s what our two-headed goblin is going to look like so far. I’ve highlighted in red all the changes I’ve made to the normal goblin stat block:

Two-Headed Goblin

Small humanoid (goblinoid), neutral evil

Armor Class 13 (leather armor)

Hit Points 14 (4d6)

Speed 30 ft.

Abilities Str 8 (-1), Dex 14 (+2), Con 10 (+0), Int 10 (+0), Wis 8 (-1), Cha 8 (-1)

Skills Perception +3, Stealth +6

Senses darkvision 60 ft., passive Perception 13

Languages Common, Goblin

Challenge ? (I’ll fill this in momentarily)

Nimble Escape. The goblin can take the Disengage or Hide action as a bonus action on each of its turns.

Two-Headed. The goblin has advantage on Wisdom (Perception) checks and on saving throws against being blinded, charmed, deafened, frightened, stunned, and knocked unconscious.

Actions

Multiattack. The goblin makes two attacks with its scimitars.

Scimitar. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) slashing damage.

Shortbow. Ranged Weapon Attack: +4 to hit, range 80/320 ft., one target. Hit: 5 (1d6 + 2) piercing damage.

Here is a breakdown of the changes that I made to it:

Armor Class is 13 instead of 15. The two-headed goblin carries two scimitars with it instead of a shield.
Hit Dice are 4 instead of 2. I see the two-headed goblin being somewhere between the goblin warrior and the elite goblin boss. Therefore, I bumped its hit dice up to 4 and adjusted the math accordingly. If you need a quick hack on how to calculate average hit points, the easiest way to do it is to multiply the number of hit dice by half the die’s maximum plus 1/2, then add in the Constitution bonus (which is the Constitution modifier multiplied by the hit dice).
Perception gets expertise. Goblins normally have Wisdom (Perception) -1. But two-headed creatures get double the Perception proficiency. Being that this creature will probably clock in at a Challenge Rating below 5, that means its proficiency bonus will be +2. Therefore, its Wisdom (Perception) bonus will be +3 (2 + 2 – 1 = +3). And passive Perception is the Perception bonus plus 10, so 13.
Two-headed feature added in. I took the feature text straight from the ettin’s stat block. Why reinvent the wheel?
Multiattack added in. The two-headed goblin gets to attack twice with both its scimitars. I didn’t give it multiattack for its shortbow because it needs both hands to fire the shortbow. And with two, constantly bickering goblin heads, it’s probably good fortune they get off that first shot off in the first place!

Step #5 – Give the new monster a challenge rating.

Now that we know most of the creature’s characteristics and what its stat block will look like, we need to figure out its challenge rating.

In Dungeons & Dragons Fifth Edition there are two major factors that we calculate when determining challenge rating:

Damage output. What is the average amount of damage per round that the creature can possibly deal over the course of three rounds?
Defensive capability. Considering both its hit points and armor class, as well as any defensive features that the creature has, how likely is this creature to survive over the course of three rounds?

Anything else that doesn’t affect either of those things we can ignore. For example, while it’s cool that our new two-headed goblin has improved Perception from its two heads, having two heads does not affect its Challenge Rating in any way (see page 281).

Here are the things that affect our goblin’s challenge rating:

Damage output. How much damage can a two-headed goblin do per round?
- If our two-headed goblin attacks with both its scimitars for three rounds and hits with each attack, it will deal an average of 10 damage per round. It deals more damage using its multiattack/scimitars than using its bow, therefore that’s what we want to go off of.
- Our goblin has an attack bonus of +4.
- The Nimble Escape ability increases the goblin’s effective attack bonus by +4.
Defensive capabilities. How likely is our goblin to survive for three rounds?
- The two-headed goblin has 14 hit points.
- Without a shield, our two-headed goblin’s AC is only 13.
- The Nimble Escape ability also increases the two-headed goblin’s effective Armor Class by +4.

From there, we reference the nifty chart on page 274 of the Dungeon Master’s Guide to figure out what the two-headed goblin’s Challenge Rating will be.

Its Offensive Challenge Rating is 3. Although, it deals 10 damage on average (making it CR 1), its effective attack bonus is +8. For each +2 above the attack bonus that the CR says it should have, we raise the offensive CR by 1 level.
Its Defensive Challenge Rating is 1/2. The goblin has 14 average hit points, which would normally make it only CR 1/8. But its Armor Class is effectively 18 thanks to its Nimble Escape feature. For every 2 points of AC above the suggested AC for the CR, we raise it two levels.

Once we have the offensive and defensive challenge ratings determine, it’s simply a matter of averaging the two out, which would make it 1.75.

Quick hack: while the DMG doesn’t specify whether you should round up or down when the average comes out to a number that isn’t a whole number, I usually round up if the offensive challenge rating is higher than the defensive challenge rating and down if vice versa.

Now we know that our two-headed goblin’s challenge rating is 2.

Step #6 – Doublecheck your work.

Once you have the challenge rating decided for your creature, make sure to go back and check your work. If the challenge rating hits one of the creature’s proficiency breakpoints (at CR 5, 9, 13, and 17), you may have to go back and adjust its proficiencies.

In addition, if the creature hits a tier-based resistance or immunity breakpoint (at CR 5, 11, and 17), you might also have to adjust its effective hit points, too, which could mean a recalculation of its defensive CR!

Don’t forget to playtest it, too. Maybe you’ll discover that it has an ability that you don’t like or you think its Challenge Rating needs to be adjusted.

Here is our final two-headed goblin: