There are a great, great many monsters and creatures presented in this book that players are free to use and place into their campaigns as they wish. But what if you have an idea for a monster that isn’t presented here? The solution to this is simple: just make a stat block for it yourself! Presented here is a step-by-step method of creating your own creatures in manner akin to those presented here.
Before dedicating the time and energy necessary to making a creature of your own, try to find an existing creature already in this book that is similar to the one you have an idea for, and modify it (in lore, mechanics, or both) to suit your idea. This may prove more fruitful than you think!
Every great monster needs a name. Think of a name that properly captures the beast’s essence, its gravitas, the terror (or otherwise) that it should strike in all those that hear it.
A very important early step is how difficult your monster is, vis-à-vis its Tier. There are 7 Tiers of difficulty in I&A, numbered 0 - 6. A creature's difficulty directly influences its defenses, Health, the damage it deals, and its abilities. A monster of a given Tier is designed to be faced by 4 PCs of varying classes with no special equipment, but does not account for that monster's tactics or tendency to fight in a group; for example, a single wolf is a Tier 0 creature, however a group of 1d6+2 wolves would be a suitable encounter for a group of Tier 1 PCs.
The Tiers are as follows:
| Tier | Level Range |
|---|---|
| 0 | 0 - 1 |
| 1 | 1 - 4 |
| 2 | 5 - 8 |
| 3 | 9 - 12 |
| 4 | 13 - 16 |
| 5 | 17 - 20 |
| 6 | 20+ |
Is this creature a Monstrosity, Beast, Undead, an Other, or something else entirely? Knowing what type of creature your monster is is important to knowing its niche in the world and under what circumstances your players can/should encounter it.
A creature’s size is important for a multitude of factors. A creature’s size will inform you of its Health, its defenses, how much damage it should deal, and the scale of its threat.
A creature’s ability scores convey a great deal of information about it, primarily what it is good at and what its strengths and weaknesses are. Additionally, its ability scores will inform its defenses and saves. The highest any creature’s ability scores can go is 10, though there are exceptions for creatures such as gods and Titans.
The next step is determining the creature’s M-/R-DEF scores and its saves; these should largely be determined by its Tier, especially its M-/R-DEF. Assuming it is wearing Light, Medium, or no Armor, its Dodge score is determined by its Size Penalty + its DEX score + its AGI score (minimum 0). Its Armor, on the other hand, can be decided arbitrarily depending on the creature's Dodge and Tier. Keep in mind that, using the standard model of Weapon Proficiency advancement (i.e. under typical circumstances), PCs can only output so much damage with a given attack, so a foe's M-/R-DEF needs to exist within a range that the PCs can reasonably surpass at least sometimes. To this end, a creature's Armor score can make up for any shortcomings left by its Dodge score. While this will typically be done by the creature's natural armor, a good way to make a lower-Tier monster more of a challenge for higher-level characters would be to supply it with artificial armor.
Use this table as a guide when deciding what the final M-/R-DEF score of a creature you are designing be.
| Tier | M-/R-DEF Range |
|---|---|
| 0 | 4 - 8 |
| 1 | 8 - 12 |
| 2 | 14 - 18 |
| 3 | 20 - 25 |
| 4 | 26 - 32 |
| 5 | 34 - 40 |
| 6 | 40+ |
A creature's saves are determined by its ability scores: Fortitude is its STR + CON divided by 2; Reflex is the creature’s AGI + DEX divided by 2; Willpower is comprised of the creature's CHA + either its INT or WIS divided by 2. Each save has a bonus equal to the larger of the two scores that make up the save.
The size of a creature’s Health Die is determined by its Size, while the amount of Health it has should largely by determined by its Tier and whether it prefers to fight alone or in a group.
| Size | Health Die (Average) |
|---|---|
| Tiny | d2 (1.5) |
| Small | d4 (2.5) |
| Medium | d6 (3.5) |
| Big | d8 (4.5) |
| Large | d10 (5.5) |
| Huge | d12 (6.5) |
| Massive and Colossal | d20 (10.5) |
As for determining exactly how much Health a creature has, that is up to you to decide, and is ultimately a big factor in how difficult you want the monster to be/how long you want the fight to be, i.e. monsters with more Health will be more difficult and make for longer fights. Also, don’t forget to multiply its CON score by the number of Health Dice used and add that to its average Health, e.g. a creature with a CON score of 2 and 5 Health Dice will have 10 (2 times 5) added to its average Health. If you want to vary a creature’s Health without rolling all of its Health Dice, consider rolling a single Health Die and adding or subtracting that to its average Health depending on whether the result is odd or even, respectively.
Depending on a creature’s nature, it may be vulnerable, resistant, or immune to certain damage types or conditions, e.g. Scorched will be immune to burn damage but vulnerable to freeze damage, and snakes cannot be knocked prone.
If a creature is vulnerable or resistant to any conditions, then it has disadvantage or advantage respectively on saves against those conditions.
A creature’s speed is largely determined by its size, but is also modified by its AGI score and general body shape: for example, Tiny creatures are able to cover a lot less ground than Large ones, and quadrupeds are much quicker than bipeds. If a creature has >4 legs, add 2m/sec to its speed; aside from that, refer to the following table for determining a creature’s speed – remember a creature’s Base Speed refers to its speed when its AGI score is 0. For every .5 above 0 that a creature's AGI score increases, their Movement increases by .25m/sec.
| Size | Base Speed |
|---|---|
| Tiny | .5m/sec |
| Small | 1.5m/sec |
| Medium | 2m/sec |
| Big | 2.5m/sec |
| Large | 3m/sec |
| Huge | 3.5m/sec |
| Massive | 4m/sec |
| Colossal | 5m/sec |
Also remember that a creature may be more at home in the water or in the air than on land, in which case the above table applies to their swimming/flying speed rather than their walking speed.
This step is rather straightforward: whatever you believe your creature is good at, give it the appropriate proficiency in the appropriate skill, e.g. a land-based creature that is good at swimming should have a Swim proficiency of >3.
Some creatures, particularly nocturnal ones or those that have lived in the dark for extended periods of time, will develop special senses to help them survive in their environment, or they may have these senses as a result of arcane influence: senses like infrared vision, blindsense, or something else entirely.
Many creatures and monsters are able to speak, either physically or telepathically. If your creature can speak, consider what languages it does know, or if other creatures simply interpret what it “says” as a language they already know, such as in the case of some of the Others. Remember that Common is a language that a creature must be taught.
Determined in large part by what type of creature it is – but ultimately by you – where a creature is found either in general or by your party specifically is a very important aspect of that creature’s existence; Unliving, for example, are almost solely found on the Plane of Life.
Some creatures have abilities that do not require time to use or are simply always active. One such example of this is the Shark’s Bloodlust feature, which activates immediately upon the Shark tasting blood or dealing final damage to a creature. A creature’s passive abilities can heavily impact its difficulty.
For their attacks, most creatures will likely use their natural weapons, such as their claws or teeth. As a creature gets larger, the value of its damage die will generally increase - as shown in the table below - but this is not a hard-and-fast rule, as creatures may have varying weapons that deal different amounts of damage and bestow different effects. When determining how much damage a creature deals, keep the party’s defenses in mind: most DEF scores start at around 5-10 and increase as PCs gain levels.
| Size | Damage Die |
|---|---|
| Tiny | d2-d4 |
| Small | d6 |
| Medium | d6 |
| Big | d6 |
| Large | d8 |
| Huge | d10 |
| Massive and Colossal | d12 |
Aside from a creature’s attacks, it is important to consider whether it has any other abilities, such as innate elemancy, shapeshifting, or anything else of note. All creatures also have access to the actions listed here.
Creatures that have innate abilities (like breath weapons or the Griffin's Wing Beat ability) have areas of effect like spells, but the point of origin is always the monster themselves.
Many creatures will have loot on their person, which they usually lose possession of when they die or are otherwise defeated. Additionally, many monsters and creatures can have their hides or scales harvested to make armor, or have their organs harvested for Alchemy Ingredients - use this table as a guide. If a creature has more than one type of natural armor, then the amount of armor materials that can be harvested is split evenly between the two, e.g. a Massive monster that has both Beast Hide and Monster Scale can have up to 25 lbs. of each harvested from its body. The types of Alchemy Ingredients that can be harvested depends largely on the nature of the monster, e.g. a monster with poisonous attacks would give Poison Ingredients, but other attack types like fire or ice might give Elixir or Ether Ingredients; additionally, Alchemy Ingredients adhere to the same "split evenly" rules as armor materials.
Both armor materials and Alchemy Ingredients can be gathered via a Medicine or Survival check, however, when harvesting Alchemy Ingredients, you can add your Alchemy Supplies proficiency to the roll in addition to your INT/WIS score. Remember that this table is just a suggestion and does not need to be strictly adhered to.
| Size | Harvestable Armor | Harvestable Ingredients | Skill Check DR |
|---|---|---|---|
| Tiny | Up to 1 lb. | Up to 1 | 6 |
| Small | Up to 4 lbs. | Up to 2 | 12 |
| Medium | Up to 7 lbs. | Up to 3 | 14 |
| Big | Up to 10 lbs. | Up to 4 | 16 |
| Large | Up to 15 lbs. | Up to 6 | 20 |
| Huge | Up to 25 lbs. | Up to 8 | 25 |
| Massive | Up to 50 lbs. | Up to 10 | 32 |
| Colossal | Up to 100 lbs. | Up to 12 | 40 |