Modifying Monsters: The Basics
If you’ve been following the Dungeon Feed in recent weeks, you know that we’ve released several articles in our Monsters Mastered series aimed at helping you improve the way monsters are used in D&D. While we strive to understand and use their traits effectively, and roleplay their motivations and lore more accurately, a large part of helping these adversaries reach their maximum potential involves changing them, specifically with regard to their stat blocks.
Changing up a monster’s stat block can drastically change the way they function in and out of combat, the way the players and their characters receive them, and even add to the story of the encounter or the world at large! It also helps keep the game fresh, so players aren’t fighting the exact same monsters over and over again, or the same ones they faced last campaign. And we’re going to discuss some simple ways to do that in this week’s article!
Bear in mind, the creatures presented in ALL official D&D books (excluding named NPCs and unique creatures in the multiverse) are merely typical examples of a particular creature. Not all kobolds have the same stat block, not all orcs wield axes, and creatures besides humanoids, ogres, and beholders can become zombies. So flex those creative muscles and let's make some new monsters!
We’re going to take a look at two different stat blocks from the monster manual, and modify each one in simple ways and end up with creatures that feel quite different. These changes can be made to effectively any creature, but we’re going to use the Boar and the Cultist for our purposes today.
We’re going to modify each creature in several ways, changing some basic attributes that each stat block features: type, size, hit points, armor class/equipment, speed, and their Ability Scores.. At the end, we should have VERY distinct creatures from the ones we started with. These traits are all described in the introduction of the Monster Manual for D&D 5e.
Next up is creature type. This is a significant thing to change, because altering this element of a stat block typically changes the creature at its core. A creature’s type categorizes them into one of several broad genres of beings in the D&D multiverse: Aberration, Beast, Celestial, Construct, Dragon, Elemental, Fey, Fiend, Giant, Humanoid, Monstrosity, Ooze, Plant, and Undead. It’s not something to be changed lightly, and there should always be a good reason for an alteration here: a drastic event that affected this creature into a fundamentally different entity.
Apart from simply changing a creature’s classification from a roleplay and lore standpoint, this change can also affect gameplay. Certain class features, spells, magic items, and other game effects treat different creature types in different ways. For example, the Chill Touch cantrip gains a bonus effect on Undead, and the Charm Person spell only works on Humanoids, so changing this can have far-reaching implications.
Let’s leave the Boar as a Beast, but change the Cultist to an Undead. We can say he is a servant of Orcus, evil god of undeath, and has been granted life after death to continue to serve his dark master. Rather than a mindless, bumbling creature like a Zombie, we will have him be an intelligent Undead, closer to a Revenant or a Vampire.
Let’s start with the "big" one: size. A creature’s size affects quite a lot in terms of mechanics and roleplay, and has its advantages and drawbacks. Making a creature larger than normal makes it stand out, and can be especially intimidating to those who note its unusual size. Creatures that are unusually small usually have the opposite effect, and often lull onlookers into a sense of security or curiosity. But don’t forget to consider the game mechanics when altering this aspect as well!
Larger creatures typically have increased hit points due to their size, which is to their advantage, but they are also able to be attacked by more creatures at once and have greater difficulty finding cover or fitting into tighter spaces. Also, larger creatures wield larger weapons than smaller creatures do, and they make attacks with oversized elements of their anatomy (claws, teeth, tails, etc). Therefore, weapon attacks from Large creatures typically deal two dice of damage, Huge ones deal three, and Gargantuan ones deal 4 or more. Conversely, smaller creatures typically feature fewer hit points and weaker weapon attacks.
With those factors in mind, let’s make our Boar larger than usual. Instead of being a Medium Beast, let’s increase its size Large. You can see this has raised its Hit Points, which we will explain next. It’s also made its Tusk attack deadlier, now dealing 2d6+1 of slashing damage instead of the base creature’s 1d6+1. For consistency’s sake, we’ve also increased the bonus damage on its charge ability from 1d6 to 2d6.
Our Cultist will stay the same size. We’ll be making different changes to its stat block.
We have already revised these creatures quite a bit, but we’re just getting started! Both of these enemies need their hit points to reflect the changes we have made to them. Hit points serve only one purpose in D&D: to prevent a swift death. Player characters deal a LOT of damage, as they should, and hit points are a monster’s last line of defense against being slain and looted.
Two factors go into determining a creature’s hit points: its hit dice and its Constitution modifier. This handy chart shows the value of a creatures’ hit die based on the size of the creature.
The larger a creature is, the larger its hit die is. But how many of those hit dice should each creature have? That… is subjective. Season to taste! Give it enough to fit your concept for the creature, but not so many that it becomes absurd. Personally, I think of a creature’s hit dice similar to the way I think of a player character’s hit dice: they get a new one every level. So a “level 5” Skeleton will have more hit points than a “level 2” Skeleton.
You could also compare them to the baseline monsters, and add, subtract, or multiple those hit dice depending on how beefy you consider this specific creature compared to others of its type. Is it twice as tough as other skeletons? Double its hit dice. Is it an especially frail, small, or fragile example of its race? Take away a few hit dice.
As stated, a creature’s Constitution modifier also comes into play when determining its hit points. You add the Constitution modifier to the total once per hit die, so the more hit dice a creature has, the more significant that constitution modifier becomes. We’ll be altering those numbers later, but let’s not forget to include them at this stage.
It should be noted, by the way, that each creature’s listed hit points are an average for that type of creature. Rather than taking that average, feel free to roll for a creature’s hit points! This could manufacture a uniquely hardy or vulnerable creature, but will certainly make encountering it more memorable!
We already increased the size of our boar, so it already has its improved hit die. For our purposes, our Boar is going to be a war steed for an orc chieftain. Since this boar was likely bred to be especially tough, is fed well, and gets plenty of exercise on the battlefield, we’re going to give it some additional hit dice. We decide that it’s more than twice as hardy as an average boar, so we increase its hit dice by a little more than double. Instead of the typical 2d8+2 (11), it’s going to have 5d10+5 (32). That’s a big step up!
For our Cultist champion, we’re going to look at your average cultist’s 2 hit dice. So they’re comparable in terms of their Hit Points to a level 2 character. I want this Cultist to be more significant, on par with a level 6 character with regard to his hit points, so we’re going to give him 6 hit dice. Since his size hasn’t changed, he’s still using d8s as his hit dice. This means his maximum hit points have risen from a meager 9 (2d8) to a 27 (6d8)!
Speed is a simple thing to modify, but a significant one. There’s no math involved in calculating a creature’s speed, it is not based on any Ability Score, or even on a creature’s size. But changing this value can have a big impact on how that creature plays.
Remember, the average speed for most player character races and classes is 30 feet. Some character builds can be a little slower, and some can be much faster, but most of them comfortably fit here. If a creature is even a little bit slower than the party, they can kite the monster, harrying it with attacks while always staying one step ahead of it. This drastically reduces the threat posed by a creature, unless you’re facing it in a confined space. Conversely, a creature that can turn that tactic on the party becomes incredibly difficult to deal with and decidedly more dangerous. And even if the party attempts to flee, a swift creature can cut off or prevent their escape. Even an alteration of 5 feet slower or faster can radically change the face of a combat encounter, so I urge Dungeon Masters to be judicious when tampering with a creature’s speed.
As far as our example creatures are concerned, I don’t feel the need to change either of their movement speeds. Let’s leave them as they are.
Armor Class / Equipment
Next up is a tricky one: gear. There is an entire chapter in the Player's Handbook outlining all manner of weapons, armor, and adventuring equipment that the players can buy and use for themselves. Some of this kit can be looted from their enemies as well… so it stands to reason that the bad guys have access to this same arsenal. Obviously intelligent creatures like humanoids possess the wherewithal to use the right tool for the situation, and are not limited to the one or two weapons presented in their stat blocks, or the style of armor listed. But even monstrous brutes can be outfitted with different accouterments by their allies or masters. Seeing an especially vulnerable, protected, or well-armed version of a familiar enemy will make them stand out against the rank and file enemies of your campaign!
When equipping armor to a creature that doesn’t typically have it, or when changing the armor worn by a particular creature, be sure to follow the restrictions that armor may place upon them. Some armors allow a creature to include its Dexterity modifier as a bonus to its armor class, others do not, or place a maximum limit on that number. Some armors are noisy to wear and move in, making Dexterity (Stealth) checks more difficult. Be sure to take these factors into account. Also note that if a creature has any Natural Armor, like our Boar does, any armor it wears replaces its natural defenses. Equipped armor and Natural Armor do not stack.
As such, it is outfitted with some crude armor that the tribe scavenged from the battlefield (completely unrelated, but I would love to see an orcish version of MTV’s 2000s television show Pimp my Ride). Reading through the different armors in Chapter 5 of the Player’s Handbook, half plate is the closest to what I have in mind. So let’s increase the Armor Class of this boar from having no armor to wearing an approximation of half plate, raising its Armor Class from an 11 (Natural Armor 11 + Dexterity modifier) to a 15 (Half plate 15 + Dexterity modifier [max 2]).
As for our undead Cultist, he was raised from death to be a champion of Orcus. We are going to give him an arsenal that reflects that. He’s outfitted in the finest armor his fellow Cultists can provide: a set of plate mail. For added defense, he also bears a shield. This is a major upgrade from the leather armor most Cultists wear, and raises his armor class from a paltry 12 (Leather armor 11 + Dexterity modifier) to a whopping 20 (Plate 18 + Shield)! But let’s not stop there. A Cultist’s only listed weapon is a scimitar, and that doesn’t scream “champion of Orcus,” so let’s upgrade that to a warhammer. This will allow him to deal more damage each turn in combat (normally a warhammer having the versatile property, could be wielded in two hands for some increased damage, but since we plan on this Cultist always having his shield, I am leaving that out of the stat block for ease of use). Of course, our cultist isn’t particularly strong, so this weapon might seem ill-suited for him… but we’re going to fix that.
Now we’re ready to change those all-important Ability Scores for these creatures! As with player characters, a monster’s Ability Scores inform many other numbers on their character sheet. A creature’s Strength can affect its damage output. Dexterity can do the same, and also often affects that creature’s Armor Class. Constitution contributes to a creature’s hit points, and Wisdom is calculated into a creature’s Passive Perception and, alongside Intelligence and Charisma, can determine the efficacy of a spellcasting creature’s magic. Of course, these numbers also signify a creature’s aptitude with certain skills and saving throws, with or without proficiency in those areas. Finally, any Difficulty Classes listed in a monster’s effects or abilities that the player characters might have to resist with their own saving throws are based on its Ability Scores as well. Because of this, modifications made to the Ability Scores in a creature’s stat block are especially impactful!
When preparing to revamp a creature’s ability scores, remember that a score of 10 is considered to be the baseline. An average human adult possesses a 10 in each listed Ability Score. Numbers below 10 should therefore only be used if a creature would be considered inferior to an average Joe with regard to that ability, and higher numbers should be employed if a creature’s abilities would surpass that of a typical human. Also remember that a score of at least 1 is required for a creature to function as a living being, and that a score of 20 is considered to be the limits of human possibility. Of course, monsters are not constrained by human limitations, and other factors in a magical world can cause even ordinary humans to surpass these limits, but it is a factor to bear in mind.
Very few creatures across the breadth of D&D are exemplary in all of their Ability Scores. Most have one or two that are intentionally higher or lower than the rest, giving the creature built-in strengths and weaknesses that player characters will have to discover and deal with.
Since these scores can affect other numbers in the stat block, be sure to reexamine other parts of the stat block if you change any.
Our Boar is meant to be particularly strong and healthy, well-used to combat, and unusually large. With that in mind, we’re going to increase its Strength, Constitution, and its Wisdom (as it needs to be better able to perceive threats on the battlefield). Compared to other, smaller boars, it is not any more or less dexterous or intelligent, so we will leave those numbers be. However, since it is larger and therefore more intimidating and commanding, we will raise its Charisma a bit. Our new big, battle-hardened Boar’s Ability scores will be as follows:
Notice that the increase in its Constitution score also increased its hit points, bringing it from a 32 (5d10+5) to a 42 (5d10+15)! Its increased Strength not only made its Tusk attack more likely to hit (from a +3 to a +6) but also the damage dealt when it lands the attack (2d6+1 to 2d6+4). It also raises the DC to resist its Charge ability (from DC 11 to DC 14)! Because its Wisdom increased, our Boar's Passive Perception was proportionally improved.
Our Cultist is radically different from where we started, so we have some changes to make to him, too. As an undead, it’s easy to believe that he is not necessarily as coordinated as he was in life. He’s also probably not as interested in self-preservation. After all, why get out of the way of an attack when you’ll feel no pain? So we’re going to lower his Dexterity score. Also, he’s probably a little less suave and collected as a corpse, so we can lower his Charisma a bit too. But as an undead, he’s certainly hardier than an average person, so we can increase his Constitution. And Orcus likely chose a qualified warrior to serve as his champion, not a run-of-the-mill minion, so it stands to reason we can increase his Strength as well… but probably not as high as that of a giant boar. Finally, let’s leave his Wisdom and Intelligence where they are. So let’s make the following changes:
As you can see, his hit points were increased thanks to that Constitution bump, leaping from a 27 (6d8) to a 39 (6d8+12)! And he’s now significantly more of a threat with that warhammer (+2 to hit for 1d8 bludgeoning damage increased to a +5 to hit for 1d8+3 damage). Lowering his charisma hurt his Charisma (Deception) bonus too. The change to his Dexterity score doesn’t affect any other numbers in the stat block (remember, the armor we chose does not include his Dexterity modifier), but it will become important when the cultist rolls initiative or has to make Dexterity saving throws.
Now we can name these creatures! We need to call them something to signify that they are different from the stat blocks that spawned them. While we could certainly give them unique identities and proper names, giving them a distinct title is also fine. These titles might include some of the alterations we made to the stat blocks, signifying the differences between them and the base versions of these creatures.
Did you happen to catch that the names chosen for these creatures subtly open the possibility for more versions of these same monsters! If this is an Armored Dire Boar, that implies that there are other Dire Boars out there that might not have armor. Or possibly that Dire Boars might be equipped with other gear that makes them unique? Would a Razortusk Dire Boar have axeblades mounted on its tusks? Probably! Possibilities abound! Similarly, a Cult Champion of Orcus is an undead creature, but a Cult Champion for Asmodeus might be more fiendish in nature! Make that one next!
Challenge Rating / XP
Because we have altered the danger presented by these monsters, the re is a greater likelihood that they might injure or kill a player character. Therefore, they represent a greater challenge, and should net the party more XP when they are defeated. Challenge Rating and XP are subjects of much debate and controversy in the D&D community, and there is too much to discuss to outline a hard and fast rule here in just a few sentences. But it bears mentioning that the reward for any sort of encounter should match the trial that was faced. If you make a monster stronger, offer a greater reward than the base monster confers. If you make one weaker, feel free to offer only a fraction of the original value.
Throughout this process, we haven’t done anything terribly technical or difficult. Small, simple changes to an existing stat block can make an entirely different monster altogether, as you can see! And using an existing stat block as a base meant that we didn’t have to start from scratch. Each monster came away with some lingering abilities that we didn’t discuss: the Cultist’s Dark Devotion, and the Boar’s Relentless trait. These qualities make the final product still recognizable as part of the original group of creatures that spawned it (boars and cultists), and give you excellent tools to use as you play these creatures.
And the fun of modifying monsters doesn’t have to stop there! There’s SO much more we could do! For example, that Cult Champion really needs a multiattack, probably knows a few spells, and really ought to have a good ability to rally his fellow cultists behind him if he's really going to reach his potential! Adding saving throws, languages, abilities, actions, reactions, even Mythic and Legendary actions can alter a creature further still! We’ll dive into all of these in future articles!
In the meantime, we’d love you to share some of your modified monsters with us! What did you change? How did these new creatures fit into your story and your world? How did your players handle them? Reach out to us on Twitter, Facebook, Instagram, or in our Discord community to fill us in!
Rob Franklin (@thedndwannabe) has been a Dungeon Master for many years, and has a deep passion for roleplaying games. He runs the MistyMountainStreaming channel on Twitch, our Misty Mountain Gaming YouTube channel, and is cohost of the Bardic Twinspiration D&D podcast. He also enjoys bourbon, From Software games, and his dog Bigby.