You and your party step into the dimly-lit main chamber of the dungeon you've been exploring for the past three sessions. After countless looting moments and party bonding, you're finally ready face what awaits you in the large, circular room.
You step forward, and something lumbers out of the ark with a roar. Roll initiative!
Monsters are a great way of adding diversity and excitement to your D&D games. But how exactly do you break down and understand a monster's stat block? What do all of the numbers mean, and how can you use them to your advantage? Even better, how and why should you create customized monsters for your next encounter?
Here are my answers to some of these exciting questions. Let's learn all about monsters in Dungeons and Dragons.
Why would you want to build a D&D monster?
D&D already has a bunch of excellent monsters you can pull from listed on the official site, which makes running games easier for new DMs. But what if you're a little more experienced, or you have a unique idea that you can't find a good match for in the existing database of official content? That's when you dive into homebrew.
Homebrew, the name given to fan-made creations outside of the published content of D&D that are for personal use in home games, can be a great way to add an element of surprise to your games for players of all experience levels. Players who've been in campaigns before will probably know how to fight a gelatinous cube or displacer beast, but what about a giant killer rabbit or an ancient Sumerian mummy with sorcerous powers? It's a great way to both even the playing field for new and experienced players and get them invested and excited about combat and the world you're building.
If you're creating full campaigns or modules to sell or share under the Open Game License (which, yes, can be a little concerning at the moment), building your own monsters is a great way to set your adventure apart and make it appealing to your audience; it gives them new territory to explore and, in a business sense, adds unique value to the product you're creating.
Beyond that, though, knowing how to build a monster helps you understand how the existing database of monsters was built in the first place, and why they were built that way. It gives you a better understanding of the mechanical structure of a monster stat block and can help give you an advantage when learning to fight against them as a player.
A Crash Course in Dungeons and Dragons Monster Stats
Before you can build a monster, you have to know what they look like, so let's look at an example and I'll explain what each part of the monster stat block does.
Here we have the stat block for a Harpy, a half-person half-bird monster pulled from Greek mythology. We can break its stat block down into five basic sections.
The Heading tells you the monster's name, size, type, and alignment. Its size and type help you figure out what spells and attacks are going to work on it and how much room it takes up. Its alignment tells you if it can be reasoned with or become an ally, or if it won't take anything but death as an answer. For this example, the Harpy is a Medium Monstrosity, meaning it is about the size of your average person and counts as a monster for spells (so for example, Hold Monster would affect it). It's also Chaotic Evil, which means that it only cares about its own interests and will attack you just for fun; you're probably not going to be able to reason with it.
The Hit and Move section, as I've labeled it, tells you exactly that - how hard this thing is to hit, how many hits it can take, and its movement speeds and types. A Harpy has an Armor Class of 11, which means that you need to roll at least an 11 on your attacks to hit it. It has roughly 38 hit points, which means that, depending on your level, it'll probably take a few hits before going down. It has a 20-foot walking speed, which is slower than average (average is 30 feet) but it also has a flying speed of 40 feet, which means it's more likely to attack you from the air than from the ground.
The Stats section is...well, exactly that. The six key stats for monsters are the same as they are for players, so you can see how well they stack up against your party and what kinds of attacks might work best on them. For example, Harpies have good Charisma scores, so trying to Charm them isn't a great idea, but their Intelligence is really weak, so trying to trick them with an Illusion might work better.
The Extras and Loopholes section tells you: whether the creature can speak and, if so, what languages; what its senses are - whether it can see in the dark or hear really well, that kind of thing; what its challenge rating is, or how hard it is to beat on its own; and what kinds of immunities, resistances, and vulnerabilities it has. A Harpy isn't immune or resistant to anything, but it's also got no specific vulnerabilities. It speaks only Common and has a completely average passive Perception score. Overall, a Harpy is a very easy monster to beat with level 1 players, so its challenge rating is really low at a 1 (more about this score later). Knowing these things can help you determine the best strategies for defeating it.
The How It Hits section tells you all of the actions that this monster can take on its turn in a fight, whether that's melee or ranged attacks, spells, or, in the case of some bigger monsters, legendary actions - big, powerful attacks and effects that have extremely limited uses. This might also be the section that describes any special features the monster has, like the ability to gain advantages by working in groups (called Pack Tactics). Harpies can claw, club, and use a magic song effect; they also attack multiple times.
Each of these sections tells you something about the monster that, for players, gives you more information about how to defeat, outwit, or befriend it and, for DMs, gives you more information about how to react to your players' decisions. Remember, the goal of a monster in D&D is to make the game more fun, challenging, and engaging in some way, whether that's giving the party something to beat down in a fight or offering them some kind of puzzle to solve.
How to build your monster
How you build your monster is going to change depending on a couple of things (usually the story relevance of your monster and whether it's meant to be fought alone or in groups), but will generally look something like this:
Decide basic facts about your monster (how hard it is to fight, what kind of monster it is, and how big it is)
Make it into a challenge to fight (hard to hit, interesting stats, interesting attacks)
Make it unique (adding bonus material)
Decide how hard the monster is to fight
The first thing I like to look at when picking or creating a monster for my games is their challenge rating or CR. As I mentioned, a monster's CR is a rating from 0 all the way up to 30 which tells you how difficult it is to beat it.
The Dungeon Master's Guide (DMG) gives a great explanation of how to determine a monster's CR on page 273. Here, it is explained to us that monster CRs are based on whether they could be relatively easily matched in the average encounter with a group of 4 adventurers of the same level. So, as mentioned, a party of four level-one players would be well-matched against a CR 1 monster.
You can adjust the CR up and down depending on the number of players in the party, their collective levels, and how hard you want the encounter to be. Remember that you don't have to send in just one monster, either - a group of CR 1/4 monsters can be a real challenge to fight!
Decide what your monster's type is
Now that you've figured out how hard your monster is going to be to fight, figure out what kind of monster it is. Is it a monster your party might have a chance to reason with? Is it an unthinking killing machine? Is it a small fluffy animal?
There are 14 different kinds of creatures your characters can encounter in D&D:
Aberrations are, by definition, creatures that aren't from the world your players are from. This might mean they're literal aliens, like illithids, or they're from other planes of existence, like eldritch monsters.
Beasts are...well, beasts. They're your typical animals - bears, owls, cats, pigs, etc. These are the things your Druid can turn into and may stop to ask questions of frequently.
Celestials are either divinity or divinity-adjacent. That means if it's a god or related to a god - like an angel - it's a celestial. Funnily enough, this category includes pegasi.
Constructs are beings that were created by other beings, like robots, golems, and automatons.
Dragons...do I need to explain this one? They're kind of in the name - massive, reptilian, able to kill you with their breath one way or another.
Elementals are creatures that come from the elemental planes - air, earth, fire, or water. They include things like genies and stalkers.
Fey are creatures that originate in the fey realms or have a deep connection to nature - think the scarier parts of fairytales and some aspects of various Celtic nations' folklore.
Fiends are the opposites of celestials - they come from the lower planes (basically Hell and the like) and include devils, demons, and other spooky things like that.
Giants are humanoids, but BIG. Anything that's vaguely humanoid but bigger than a Goliath is probably a giant.
Humanoids are probably what most if not all of your players will be playing. If it's got two legs, limited magical capabilities (sometimes), and can talk to you, it's probably a humanoid.
Monstrosities are classical monsters - things that aren't normal animals but do technically originate from the main plane of existence. This includes things like owlbears and minotaurs, among many, many others.
Oozes are a fun category because they're basically just semi-sentient slime.
Plants...yep. Includes regular plants and fungi. Yes, these can sometimes be homicidal.
Undead are any of the above but brought back after they've died without a proper resurrection spell. This includes ghosts, ghouls, skeletons, vampires, liches, and many more.
Decide how big it is
Okay, so you've got a monster of a certain type with solid CR. So, how big is it? D&D monsters exist on a set sizing scale, so they can be easily categorized for spells and other effects. They are measured by how much room they take up on the battlefield in a square space.
Tiny - 2.5ft by 2.5ft
Small - 5ft by 5ft
Medium - 5ft by 5ft
Large - 10ft by 10ft
Huge - 15ft by 15ft
Gargantuan - 20ft by 20ft or bigger
Your average party is going to be made up of Medium creatures, though occasionally, you'll get a Small creature in there. Most humanoids are Medium creatures with the exception of goblins, harengon (sometimes), and a few other shorter races.
A good idea is to figure out the size of your monster based on how many you want to have on the field and how many party members you have. For example, a swarm of Tiny creatures might make for a good encounter, as each can be easily beaten on its own and the grouping makes them more of a challenge. You wouldn't create a swarm of Medium creatures, though; it's likely that it will take the full attention of at least one of your party members - maybe two - to take it down, so having too many on the field can be frustrating and overwhelming. In that case, you'd want only about as many Medium creatures as half your party count. For Large or Huge creatures, you'll usually only want one on the field at a time for an average-sized party. Gargantuan creatures should be saved for special encounters and higher-level parties.
Make it hard to hit
A monster that's too easy to hit isn't fun, but a monster that's too hard to hit is frustrating, so finding that appropriate balance is essential to creating a great monster.
When you're figuring out how hard it'll be to hit, you'll want to consider three basic things: its AC, its speed, and its Dexterity.
As mentioned, a monster's Armor Class or AC is the number your players have to beat when they're rolling to hit. This is usually a number between 10 and 20, though some really difficult monsters have ACs higher than 20.
A monster's speed is measured in the number of feet it can move in a round (6 seconds). A fairly normal speed is around 30 ft., though some monsters can move as fast as twice that or more. You'll also want to consider whether this monster can fly, swim, burrow underground, or move in some other special way, and figure out how quickly they can do that. For more variety, you might try making an alternative movement speed faster or slower than its standard speed.
Dexterity for monsters is the same as it is for players - it's one of the six key stats and controls how quickly and accurately your monster can react. High Dexterity scores mean that your monster is agile and good at dodging attacks, while low Dexterity scores mean it's more likely to take a hit if you aim for it.
Try to balance these three factors as well as you can. If your monster has a high AC, for example, you might want to make it slow or not great at dodging. If it's super agile and fast, its AC should be low. If it's really fast but has terrible Dexterity, a higher AC might benefit it. And so on, and so on.
Experiment with different combinations to see what suits your monster's attack and defense styles.
Give it stats
Now that your monster is difficult to hit, it's time to find out more about how it's going to interact with your players - it's time to give it stats. As mentioned above, D&D monsters use the same six key stats that players do: Strength, Dexterity, Constitution, Intelligence, Wisdom, and Charisma. These stats control the same things for the monsters that they do for the players, from saves and attacks in battle to roleplay elements.
For monster stats, you can choose to roll or use a point-buy system if you really want to, but my favorite method for doing this is to simply pull up a comparable monster from the existing canon. Let's say, for example, that I wanted to create a smart, mind-melting monster that isn't physically strong or fast. I might look at the stats for something like a Mind Flayer - a Medium Aberration creature that can pull the brain from your players' bodies - and adjust from there. Maybe I want it even weaker physically, or maybe I want it to be stronger and more of a challenge.
When using existing stats, try to look for creatures of a similar size and type to the monster you're creating for the closest match.
Give it attacks
We know all about how it moves, so now, let's make it move. Let's give your monster attacks!
The attacks that a monster has are largely based on the kind of monster you're making and the theme surrounding them. For example, a brain-munching monster is going to do lots of psychic damage, but might not have strong physical attacks, and may instead focus on evading your players. A big brutish physical monster, on the other hand, might have devastating physical damage - bludgeoning, piercing, slashing, etc. - but might not be quick to get out of the way or may be weaker to magical attacks.
My best piece of advice for giving your monster an attack moveset is to consider how your characters are likely to try and fight it. Give it a couple of direct hitters, attacks designed to specifically go after your players, and a couple of surprises. Give it a way to avoid attacks or move around the arena unexpectedly. Basically, you're trying to make the fight interesting from a strategic standpoint.
As always, you can look to existing monsters for inspiration when it comes to attacks. Consider the moveset of the creature you used to model the stats and see how you might implement something similar, or what you might want to change.
The best places to make D&D monsters
Now obviously, you don't need any special equipment to make a D&D monster. You can use a pen and paper or a digital word processor and come up with a great monster - all you need is reference material and imagination. That being said, there are sites and programs you can use that will make the process easier.
DnDBeyond is Wizards of the Coast's official website for Dungeons and Dragons as a franchise. It's also a great tool for players and DMs. You can use it to create characters and, yes, homebrew things like items and monsters. Creating a DnDBeyond account is free and gives you access to an entire community of other players and DMs via their homebrew directory and forums.
To create a monster in DnDBeyond, sign in and then select the "Homebrew" tab in the menu. From there, you'll be able to select "Create homebrew" and fill in the details of what you want to make. The wonderful thing about this is that you'll have all of the basic rules available to you for free, which means you can easily take a monster as a template and simply customize it from there. Another awesome bonus of this site is that you can share your homebrew monsters with others for them to use!
If you like the look of D&D monster stat blocks but want a bit more freedom when it comes to format and design - and if you're not afraid to learn a little bit of elementary coding - then Homebrewery from Natural Crit is the tool for you. This website lets you type in the code for your monster's stat block and download it as a high-quality PDF that mimics the formatting and style of the official books. It uses a form of Markdown and CSS to do this, but it's incredibly user friendly. There are templates for almost anything you want to make and plenty of helpful tutorials available online.
To create a monster stat block, open a new page and look in the menu for the tab that reads "PHB." From here, you can select from one of three monster stat block styles - framed, unframed, and wide - depending on how you'd like your block to sit on the page. It'll auto-generate a sample monster that you can then simply customize into your own creation (plus, the auto-generations are quite cute and funny to read through).
If you want the most customization power possible, you might try creating your stat block in a digital design tool. My favorite is Canva, a free digital design platform that allows you to create designs in any size for videos and still images. It has a wonderful wealth of templates you can use - this one is great for D&D things - but doesn't restrict you to that. You can create completely from scratch for a totally customized block.
Monsters are such a crucial part of the D&D experience that it surprises me how little they're talked about on a basic level. Most discussions I've seen are high-level analyses of specific mechanics and balancing, which is all well and good but comes across as garbaldegook if you've never seen a stat block or fought against a monster before. Having a solid foundational understanding of monsters, as well as a beginning-level set of knowledge for creating your own, can make jumping into DMing - the most complicated part of the game - a lot less intimidating and a lot more exciting.
Now go out there and bring your creatures to life!