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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.

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 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.

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
21 400 37 31 24 130 98 27 20 23 18
22 400 36 32 25 140 105 28 21 23 18
23 480 40 33 26 150 113 29 22 24 19
24 520 42 35 27 165 124 30 23 25 20
25 560 43 36 28 180 135 30 24 26 21
26 600 44 37 29 195 145 31 25 27 22
27 640 45 38 30 210 155 32 26 28 23
28 680 46 39 31 225 165 33 27 29 24
29 720 47 40 32 240 175 34 28 30 25
30 760 48 41 33 255 185 35 29 31 26

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.

Table: Average Die Results
Die Type Average Result*
d4 2.5
d6 3.5
d8 4.5
d10 5.5
d12 6.5
d20 10.5

* Always round down after multiplying. For example, treat the average of 1d4 as 2, and the average of 2d4 as 5.

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.

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

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 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.

Step 4: Size

Table: Size
Size Minimum CR Maximum CR Base Str Base Dex Base Con
Fine 2 1 18 8
Diminutive 4 1 16 8
Tiny 6 2 14 8
Small 6 12 8
Medium 10 10 10
Large 2 18 8 14
Huge 4 26 6 18
Gargantuan 6 34 6 22
Colossal 8 42 6 26

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). 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 skills are determined by its type (see creature types). Creatures with a low Intelligence typically only have ranks in Dexterity- and Strength-based skills.

Table: Creature Statistics by Type
Type Hit Die Base Attack Bonus (BAB) Good Saving Throws Skill Ranks* Class Skills
Aberration d8 HD × 3/4 (Medium BAB) Will 4 + Int mod per HD Acrobatics, Climb, Escape Artist, Fly, Intimidate, Knowledge (pick one), Perception, Spellcraft, Stealth, Survival, and Swim.
Animal d8 HD × 3/4 (Medium BAB) Fort, Ref 2 + Int mod per HD Acrobatics, Climb, Fly, Perception, Stealth, and Swim.
Construct d10 HD (Fast BAB) 2 + Int mod per HD None
Dragon d12 HD (Fast BAB) Fort, Ref, Will 6 + Int mod per HD Appraise, Bluff, Climb, Craft, Diplomacy, Fly, Heal, Intimidate, Knowledge (all), Linguistics, Perception, Sense Motive, Spellcraft, Stealth, Survival, Swim, and Use Magic Device.
Fey d6 HD × 1/2 (Slow BAB) Ref, Will 6 + Int mod per HD Acrobatics, Bluff, Climb, Craft, Diplomacy, Disguise, Escape Artist, Fly, Knowledge (geography), Knowledge (local), Knowledge (nature), Perception, Perform, Sense Motive, Sleight of Hand, Stealth, Swim, Use Magic Device.
Humanoid d8 HD × 3/4 (Medium BAB) Varies (any one) 2 + Int mod per HD Climb, Craft, Handle Animal, Heal, Profession, Ride, and Survival (plus any gained from class levels.)
Magical beast d10 HD (Fast BAB) Fort, Ref 2 + Int mod per HD Acrobatics, Climb, Fly, Perception, Stealth, Swim.
Monstrous humanoid d10 HD (Fast BAB) Ref, Will 4 + Int mod per HD Climb, Craft, Fly, Intimidate, Perception, Ride, Stealth, Survival, and Swim.
Ooze d8 HD × 3/4 (Medium BAB) 2 + Int mod per HD None
Outsider d10 HD (Fast BAB) Varies (any two) 6 + Int mod per HD Bluff, Craft, Knowledge (planes), Perception, Sense Motive, and Stealth (plus 4 additional.)
Plant d8 HD × 3/4 (Medium BAB) Fort 2 + Int mod per HD Perception and Stealth.
Undead d8 HD × 3/4 (Medium BAB) Will 4 + Int mod per HD Climb, Disguise, Fly, Intimidate, Knowledge (arcana), Knowledge (religion), Perception, Sense Motive, Spellcraft, and Stealth.
Vermin d8 HD × 3/4 (Medium BAB) Fort 2 + Int mod per HD None

* 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.

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: Statistics Summary for a quick feat calculation chart.

Step 7: Other Statistics

Table: Statistics Summary
HD Fast BAB Medium BAB Slow BAB Good Save Bad Save Feats
1 +1 +0 +0 +2 +0 1
2 +2 +1 +1 +3 +0 1
3 +3 +2 +1 +3 +1 2
4 +4 +3 +2 +4 +1 2
5 +5 +3 +2 +4 +1 3
6 +6 +4 +3 +5 +2 3
7 +7 +5 +3 +5 +2 4
8 +8 +6 +4 +6 +2 4
9 +9 +6 +4 +6 +3 5
10 +10 +7 +5 +7 +3 5
11 +11 +8 +5 +7 +3 6
12 +12 +9 +6 +8 +4 6
13 +13 +9 +6 +8 +4 7
14 +14 +10 +7 +9 +4 7
15 +15 +11 +7 +9 +5 8
16 +16 +12 +8 +10 +5 8
17 +17 +12 +8 +10 +5 9
18 +18 +13 +9 +11 +6 9
19 +19 +14 +9 +11 +6 10
20 +20 +15 +10 +12 +6 10
21 +21 +15 +10 +12 +7 11
22 +22 +16 +11 +13 +7 11
23 +23 +17 +11 +13 +7 12
24 +24 +18 +12 +14 +8 12
25 +25 +18 +12 +14 +8 13
26 +26 +19 +13 +15 +8 13
27 +27 +20 +13 +15 +9 14
28 +28 +21 +14 +16 +9 14
29 +29 +21 +14 +16 +9 15
30 +30 +22 +15 +17 +10 15

Using Table: Monster Statistics 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.

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. 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. Resistance and immunities become more common above CR 10. As a general rule a creature's resistance 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.

Table: XP and GP values by CR
CR XP Slow GP Medium GP Fast GP
1/8 50 XP 20 gp 35 gp 50 gp
1/6 65 XP 30 gp 45 gp 65 gp
1/4 100 XP 40 gp 65 gp 100 gp
1/3 135 XP 55 gp 85 gp 135 gp
1/2 200 XP 85 gp 130 gp 200 gp
1 400 XP 170 gp 260 gp 400 gp
2 600 XP 350 gp 550 gp 800 gp
3 800 XP 550 gp 800 gp 1,200 gp
4 1,200 XP 750 gp 1,150 gp 1,700 gp
5 1,600 XP 1,000 gp 1,550 gp 2,300 gp
6 2,400 XP 1,350 gp 2,000 gp 3,000 gp
7 3,200 XP 1,750 gp 2,600 gp 3,900 gp
8 4,800 XP 2,200 gp 3,350 gp 5,000 gp
9 6,400 XP 2,850 gp 4,250 gp 6,400 gp
10 9,600 XP 3,650 gp 5,450 gp 8,200 gp
11 12,800 XP 4,650 gp 7,000 gp 10,500 gp
12 19,200 XP 6,000 gp 9,000 gp 13,500 gp
13 25,600 XP 7,750 gp 11,600 gp 17,500 gp
14 38,400 XP 10,000 gp 15,000 gp 22,000 gp
15 51,200 XP 13,000 gp 19,500 gp 29,000 gp
16 76,800 XP 16,500 gp 25,000 gp 38,000 gp
17 102,400 XP 22,000 gp 32,000 gp 48,000 gp
18 153,600 XP 28,000 gp 41,000 gp 62,000 gp
19 204,800 XP 35,000 gp 53,000 gp 79,000 gp
20 307,200 XP 44,000 gp 67,000 gp 100,000 gp
21 409,600 XP 56,000 gp 84,000 gp 126,000 gp
22 615,000 XP 70,000 gp 105,000 gp 158,000 gp
23 820,000 XP 88,000 gp 132,000 gp 198,000 gp
24 1,230,000 XP 110,000 gp 165,000 gp 248,000 gp
25 1,640,000 XP 138,000 gp 208,000 gp 312,000 gp
26 2,457,600 XP 820,000 gp 614,400 gp 409,600 gp
27 3,276,800 XP 1,092,000 gp 819,200 gp 546,000 gp
28 4,915,200 XP 1,640,000 gp 1,228,800 gp 819,200 gp
29 6,553,600 XP 2,184,000 gp 1,638,400 gp 1,092,000 gp
30 9,830,400 XP 3,280,000 gp 2,457,600 gp 1,638,400 gp

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.