Monster Creation

Creating a monster is part science and part art. While most monsters follow a general pattern of their overall power and abilities as related to their Challenge Rating (CR), there are many exceptions. Some monsters, for example, have significantly more hit points or a higher AC than the average for their CR, but make up for this advantage by being weak in other areas. Other monsters have significantly higher average damage, but have a lower attack bonus.

Building the Monster

The following guidelines are provided to assist in monster creation and to help balance a creation for its CR.

Step 1: Concept

The first step in creating a new monster is to define its concept and role in the game. Generally, this involves picking the monster's CR, type, physical appearance, and manner of fighting. Once you have these basic pieces of information, you should find a number of similar monsters of the same type and roughly the same CR for comparison purposes.

Table: Monster Statistics by CR

CR	Hit Points	Armor Class	High Attack	Low Attack	Average Damage		Primary Ability DC	Secondary Ability DC	Good Save	Poor Save
					High	Low
1/2	10	11	1	0	4	3	11	8	3	0
1	15	12	2	1	7	5	12	9	4	1
2	20	14	4	3	10	7	13	9	5	1
3	30	15	6	4	13	9	14	10	6	2
4	40	17	8	6	16	12	15	10	7	3
5	55	18	10	7	20	15	15	11	8	4
6	70	19	12	8	25	18	16	11	9	5
7	85	20	13	10	30	22	17	12	10	6
8	100	21	15	11	35	26	18	12	11	7
9	115	23	17	12	40	30	18	13	12	8
10	130	24	18	13	45	33	19	13	13	9
11	145	25	19	14	50	37	20	14	14	10
12	160	27	21	15	55	41	21	15	15	11
13	180	28	22	16	60	45	21	15	16	12
14	200	29	23	17	65	48	22	16	17	12
15	220	30	24	18	70	52	23	16	18	13
16	240	31	26	19	80	60	24	17	19	14
17	270	32	27	20	90	67	24	18	20	15
18	300	33	28	21	100	75	25	18	20	16
19	330	34	29	22	110	82	26	19	21	16
20	370	36	30	23	120	90	27	20	22	17

Step 2: Target Statistics

Once you have a creature's type and CR determined, use Table: Monster Statistics by CR to determine its approximate statistics by CR. These values are a rough guideline only. You will notice that many of the existing monsters in this book do not follow these guidelines exactly. Most monsters excel in one of these areas, usually in the amount of damage dealt, but lag in one or two other areas to help balance them out. When referring to Table: Monster Statistics by CR, keep the following points in mind.

CR: This is the approximate CR of the monster. This number might change as design progresses.

Hit Points: This is the approximate hit point total for the monster. Note that creatures with particularly high Armor Classes or saving throws, or a number of resistances, might have a lower number. Outsiders and constructs typically have lower hit point totals.

Armor Class: This is the average Armor Class for a creature of this CR. When it comes time to design the creature's protections, keep this number in mind. Creatures with hit points above the average often have lower Armor Class values to compensate.

High Attack: This is the average total attack bonus for a creature of this CR. This value is for creatures that are primarily melee or ranged combatants. Creatures with a higher than normal average damage typically have a lower attack value to compensate.

Low Attack: This is the average total attack bonus for a creature of this CR that does not rely upon melee or ranged attacks to deal damage. This includes most creatures that rely on spells and spell-like abilities in combat.

Average Damage: This is the average amount of damage dealt by a creature of this CR if all of its attacks are successful. To determine a creature's average damage, add the average value for all of the damage dice rolled (as determined by Table: Average Die Results) to the damage modifier for each attack.

A creature that relies on melee or ranged weapons in combat should have average damage within the range of high and low damage.

A creature with higher than normal attack bonuses will often deal lower damage, while a creature with lower than normal attack bonuses will often deal higher damage.

Primary Ability DC: This is the average difficulty class (DC) for any spells, spell-like abilities, and special abilities (such as breath weapons) possessed by a creature of this CR that relies on such attacks in combat. If an ability is particularly powerful, it might have a lower DC to compensate.

Secondary Ability DC: This is the average DC for spells and special abilities for a creature that does not rely on such attacks in combat. Generally, a DC should not be lower than this number.

Good Save: This is the average saving throw bonus for a creature of this CR if the saving throw is one of the creature's good saving throws.

Poor Save: This is the average saving throw bonus for a creature of this CR if the saving throw is one of the creature's poor saving throws.

Step 3: Hit Dice

The next step in creating a monster is to determine the approximate number of Hit Dice it has. Hit Dice determine a wide variety of other statistics, including the creature's feats, skills, hit points, attack bonuses, and special ability DCs.

A creature's total number of Hit Dice depends on a number of factors, but the two most important are its CR and its type. Table: Creature Hit Dice lists the average number of Hit Dice for each creature type, depending on its CR. While many of the monsters in this book are close to these values, some are not. This is because they have higher or lower average hit points to balance out their Armor Class or resistances.

Table: Creature Hit Dice

Creature Type	Challenge Rating
	1/2	1	2	3	4	5	6	7	8	9	10	11	12	13	14	15	16	17	18	19	20
Aberration	1	2	3	4	5	7	9	10	12	14	15	16	17	19	20	22	24	26	28	30	34
Animal	1	2	3	4	5	7	9	10	12	14	15	16	17	19	20	22	24	26	28	30	34
Construct	1	2	3	4	5	6	8	9	10	12	13	14	16	18	19	20	21	23	25	28	31
Dragon	1	2	3	4	5	6	7	8	9	11	12	13	14	16	17	18	19	21	23	25	29
Fey	2	3	4	5	6	8	10	12	13	15	17	18	20	22	23	25	26	28	31	33	37
Humanoid	1	2	3	4	5	7	9	10	12	14	15	16	17	19	20	22	24	26	28	30	34
Magical beast	1	2	3	4	5	6	8	9	10	12	13	14	16	18	19	20	21	23	25	28	31
Monstrous humanoid	1	2	3	4	5	6	8	9	10	12	13	14	16	18	19	20	21	23	25	28	31
Ooze	1	2	3	4	5	7	9	10	12	14	15	16	17	19	20	22	24	26	28	30	34
Outsider	1	2	3	4	5	6	8	9	10	12	13	14	16	18	19	20	21	23	25	28	31
Plant	1	2	3	4	5	7	9	10	12	14	15	16	17	19	20	22	24	26	28	30	34
Undead	1	2	3	4	5	7	9	10	12	14	15	16	17	19	20	22	24	26	28	30	34
Vermin	1	2	3	4	5	7	9	10	12	14	15	16	17	19	20	22	24	26	28	30	32

Step 4: Size

Now that you have the creature's average statistics, it's time to pick its size. Most creatures range in size from Small to Huge, but other sizes are not uncommon. A creature's size sets a baseline for its physical ability scores and its natural weapon damage (as noted in the Natural Attacks description in the Universal Monster Rules—see Appendix 3, pages 297–306). You should pick a size that fits well with the creature's intended role in the game and Challenge Rating. If you decide to give a creature an unusual size for its CR or HD, you should justify the unusual choice in the monster's description to account for the discrepancy—in most cases, such unusually sized monsters should be highly magical in nature. See Table: Size for more information on creature sizes and expected scores.

Minimum/Maximum CR: These values list the minimum and the maximum challenge ratings a creature of the indicated size should fall between.

Base Str, Base Dex, Base Con: These list the average scores for a creature of this size. Your specific monster's Strength, Dexterity, or Constitution might vary greatly from these numbers, but if they do, you should pay close attention to how these variances affect its other statistics.

Step 5: Abilities

Once you have determined a creature's size, type, and Hit Dice, it's time to move on to its ability scores. The bonuses granted from these ability scores should increase a creature's hit points, attack bonuses, and saving throws to the approximate values presented on Table: Monster Statistics by CR.

A creature's physical ability scores (Strength, Dexterity, and Constitution) should be relatively close to the base values presented on Table: Size, depending on its size. Creatures with a few Hit Dice but a high average hit point total should have a higher than normal Constitution.

A creature's mental ability scores (Intelligence, Wisdom, and Charisma) are largely defined by the creature's concept. The base for all of these abilities is 10. Creatures that rely on spells and spell-like abilities in combat should have one mental ability score that stands out (usually Charisma). Creatures incapable of speech have an Intelligence score of 2 or lower. Unintelligent undead, constructs, oozes, plants, and vermin rarely have an Intelligence score.

Step 6: Skills and Feats

Using Table: Creature Statistics by Type, determine how many skill ranks your creature has based on its type and Hit Dice. Assign these ranks as determined by the creature's concept. A creature's class skill is determined by its type. Creatures with a low Intelligence typically only have ranks in Dexterity- and Strength-based skills.

After you have assigned skills, it's time to assign the creature's feats. Each creature with an Intelligence score receives a number of feats equal to 1 + 1 per every 2 Hit Dice after the first (so, 1 at 1 HD, 2 at 3 HD, etc.). A creature must qualify to take a feat as normal. See Table 1–6 for a quick feat calculation chart.

Step 7: Other Statistics

Using Table: Monster Statitics by CR, Table: Creature Statistics by Type, and Table: Statistics Summary, you can now determine many of the creature's other statistics.

When building a creature's Armor Class, start by adding armor, shield, and natural armor bonuses to its Dexterity modifier. If a creature does not wear armor, give it a tougher hide to get it near its average AC. Remember that creatures with higher hit point totals might have a lower Armor Class, whereas creatures with fewer hit points might have a higher Armor Class. If a creature's Armor Class deviates from the average by more than 5 points, it might not be the right CR.

When determining a creature's attack bonuses, refer to the guidelines from Table: Monster Statistics by CR based on the creature's CR. If the bonus is too low, consider increasing the creature's Strength or Dexterity, or increasing the amount of damage it deals to above the average. If the bonus is too high, consider decreasing the creature's Strength or Dexterity, or decrease the amount of damage it deals. If this value is significantly different, and the creature is intended to rely on melee or ranged attacks, consider adjusting the creature's CR.

Use Table: Average Die Results to determine the number of damage dice, combined with damage bonuses, that the creature needs to reach the average damage for its CR. The creature might need additional or more damaging attacks to approach the average. Remember that creatures that primarily deal damage with other abilities, such as spells, do not need to meet the average damage for their attacks. You can also use Table: Average Die Results to determine a creature's average hit points. Remember that PC class levels provide the maximum number of hit points at 1st level.

Repeat this process for a creature's saving throws. If the saving throws are too high, consider altering the ability scores on which they are based.

When determining a creature's speed, first decide if it has any alternative modes of movement, such as burrow, climb, fly, or swim. Most Medium creatures have a base speed of 30 feet. Quadrupeds and Large creatures increase this by 10 feet each. Smaller creatures decrease this base speed by 10 feet. If a creature is particularly fast or slow, modify the base speed by 10 feet. Burrow and climb speeds are usually half a creature's base speed, while flying speeds are roughly double. Remember to give a creature the appropriate skills for any unusual movement methods.

Table: Creature Statistics by Type

Type	Hit Die	Base Attack Bonus (BAB)	Good Saving Throws	Skill Ranks*
Aberration	d8	HD × 3/4 (Medium BAB)	Will	4 + Int mod per HD
Animal	d8	HD × 3/4 (Medium BAB)	Fort, Ref	2 + Int mod per HD
Construct	d10	HD (Fast BAB)	—	2 + Int mod per HD
Dragon	d12	HD (Fast BAB)	Fort, Ref, Will	6 + Int mod per HD
Fey	d6	HD × 1/2 (Slow BAB)	Ref, Will	6 + Int mod per HD
Humanoid	d8	HD × 3/4 (Medium BAB)	Varies (any one)	2 + Int mod per HD
Magical beast	d10	HD (Fast BAB)	Fort, Ref	2 + Int mod per HD
Monstrous humanoid	d10	HD (Fast BAB)	Ref, Will	4 + Int mod per HD
Ooze	d8	HD × 3/4 (Medium BAB)	—	2 + Int mod per HD
Outsider	d10	HD (Fast BAB)	Varies (any two)	6 + Int mod per HD
Plant	d8	HD × 3/4 (Medium BAB)	Fort	2 + Int mod per HD
Undead	d8	HD × 3/4 (Medium BAB)	Will	4 + Int mod per HD
Vermin	d8	HD × 3/4 (Medium BAB)	Fort	2 + Int mod per HD
* As long as a creature has an Intelligence of at least 1, it gains a minimum of 1 skill point per Hit Die. Creatures with an Intelligence score of “—” gain no skill points or feats.

Step 8: Special Abilities and Qualities

Monsters are different from characters in that they can have all sorts of different special abilities and qualities. Each of these is tied closely to the creature's concept, allowing it to fill a specific role in the game. For examples, look at monsters in this book. Monsters should use abilities from the Universal Monster Rules whenever possible, instead of creating new yet similar abilities—when you do create new abilities, use the Universal Monster Rules as a template for how to present and create the new abilities.

Most special abilities that cause damage, such as breath weapons, give a save (Fortitude, Reflex, or Will depending on the ability). The DC for almost all special abilities is equal to 10 + 1/2 the creature's Hit Dice + a relevant ability modifier (usually Constitution or Charisma depending on the ability). Special abilities that add to melee and ranged attacks generally do not allow a save, as they rely on the attacks hitting to be useful.

Special senses and resistances to certain energy types are common in creatures of CR 5 and lower. Damage reduction, energy immunities, and regeneration are more common in creatures above CR 5. Spell resistance and immunities become more common above CR 10. As a general rule a creature's spell resitance should equal its CR + 11.

Step 9: Treasure

A creature should have an amount of treasure appropriate to its CR. See Table: XP and GP Values by CR for a list of treasure totals based on CR. For some creatures, their treasure consists of the loot from their recent meals strewn across their lairs, while for others it consists of a greed-fueled hoard or even gear it uses in combat. Make sure to account for any weapons or armor that the creature is using, as determined by step 7.

Step 10: Details

Now that you have all of the creature's statistics sorted out, it's time to fill in all the details—such as name, alignment, space, reach, environment, and ecology—as you see fit.