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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.

Table: Monster Statistics by CR
CRHit PointsArmor ClassHigh AttackLow AttackAverage DamagePrimary Ability DCSecondary Ability DCGood SavePoor Save
HighLow
1/21011104311830
11512217512941
220144310713951
3301564139141062
44017861612151073
555181072015151184
670191282518161195
78520131030221712106
810021151135261812117
911523171240301813128
1013024181345331913139
11145251914503720141410
12160272115554121151511
13180282216604521151612
14200292317654822161712
15220302418705223161813
16240312619806024171914
17270322720906724182015
183003328211007525182016
193303429221108226192116
203703630231209027202217

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.

Table: Average Die Results
Die TypeAverage Result*
d42.5
d63.5
d84.5
d105.5
d126.5
d2010.5
*Always round down after multiplying. For example, treat the average of 1d4 as 2, and the average of 2d4 as 5.

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 TypeChallenge Rating
1/21234567891011121314151617181920
Aberration12345791012141516171920222426283034
Animal12345791012141516171920222426283034
Construct1234568910121314161819202123252831
Dragon123456789111213141617181921232529
Fey234568101213151718202223252628313337
Humanoid12345791012141516171920222426283034
Magical beast1234568910121314161819202123252831
Monstrous humanoid1234568910121314161819202123252831
Ooze12345791012141516171920222426283034
Outsider1234568910121314161819202123252831
Plant12345791012141516171920222426283034
Undead12345791012141516171920222426283034
Vermin12345791012141516171920222426283032
Table: Size
SizeMinimum CRMaximum CRBase StrBase DexBase Con
Fine21188
Diminutive41168
Tiny62148
Small6128
Medium101010
Large218814
Huge426618
Gargantuan634622
Colossal842626

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.

Table: Statistics Summary
HDFast BABMedium BABSlow BABGood SaveBad SaveFeats
1+1+0+0+2+01
2+2+1+1+3+01
3+3+2+1+3+12
4+4+3+2+4+12
5+5+3+2+4+13
6+6+4+3+5+23
7+7+5+3+5+24
8+8+6+4+6+24
9+9+6+4+6+35
10+10+7+5+7+35
11+11+8+5+7+36
12+12+9+6+8+46
13+13+9+6+8+47
14+14+10+7+9+47
15+15+11+7+9+58
16+16+12+8+10+58
17+17+12+8+10+59
18+18+13+9+11+69
19+19+14+9+11+610
20+20+15+10+12+610
21+21+15+10+12+711
22+22+16+11+13+711
23+23+17+11+13+712
24+24+18+12+14+812
25+25+18+12+14+813
26+26+19+13+15+813
27+27+20+13+15+914
28+28+21+14+16+914
29+29+21+14+16+915
30+30+22+15+17+1015

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
TypeHit DieBase Attack Bonus (BAB)Good Saving ThrowsSkill Ranks*
Aberrationd8HD × 3/4 (Medium BAB)Will4 + Int mod per HD
Animald8HD × 3/4 (Medium BAB)Fort, Ref2 + Int mod per HD
Constructd10HD (Fast BAB)2 + Int mod per HD
Dragond12HD (Fast BAB)Fort, Ref, Will6 + Int mod per HD
Feyd6HD × 1/2 (Slow BAB)Ref, Will6 + Int mod per HD
Humanoidd8HD × 3/4 (Medium BAB)Varies (any one)2 + Int mod per HD
Magical beastd10HD (Fast BAB)Fort, Ref2 + Int mod per HD
Monstrous humanoidd10HD (Fast BAB)Ref, Will4 + Int mod per HD
Oozed8HD × 3/4 (Medium BAB)2 + Int mod per HD
Outsiderd10HD (Fast BAB)Varies (any two)6 + Int mod per HD
Plantd8HD × 3/4 (Medium BAB)Fort2 + Int mod per HD
Undeadd8HD × 3/4 (Medium BAB)Will4 + Int mod per HD
Vermind8HD × 3/4 (Medium BAB)Fort2 + 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.

Table: XP and GP Values by CR
CRXPSlow GPMedium GPFast GP
1/850 XP20 gp35 gp50 gp
1/665 XP30 gp45 gp65 gp
1/4100 XP40 gp65 gp100 gp
1/3135 XP55 gp85 gp135 gp
1/2200 XP85 gp130 gp200 gp
1400 XP170 gp260 gp400 gp
2600 XP350 gp550 gp800 gp
3800 XP550 gp800 gp1,200 gp
41,200 XP750 gp1,150 gp1,700 gp
51,600 XP1,000 gp1,550 gp2,300 gp
62,400 XP1,350 gp2,000 gp3,000 gp
73,200 XP1,750 gp2,600 gp3,900 gp
84,800 XP2,200 gp3,350 gp5,000 gp
96,400 XP2,850 gp4,250 gp6,400 gp
109,600 XP3,650 gp5,450 gp8,200 gp
1112,800 XP4,650 gp7,000 gp10,500 gp
1219,200 XP6,000 gp9,000 gp13,500 gp
1325,600 XP7,750 gp11,600 gp17,500 gp
1438,400 XP10,000 gp15,000 gp22,000 gp
1551,200 XP13,000 gp19,500 gp29,000 gp
1676,800 XP16,500 gp25,000 gp38,000 gp
17102,400 XP22,000 gp32,000 gp48,000 gp
18153,600 XP28,000 gp41,000 gp62,000 gp
19204,800 XP35,000 gp53,000 gp79,000 gp
20307,200 XP44,000 gp67,000 gp100,000 gp
21409,600 XP56,000 gp84,000 gp126,000 gp
22615,000 XP70,000 gp105,000 gp158,000 gp
23820,000 XP88,000 gp132,000 gp198,000 gp
241,230,000 XP110,000 gp165,000 gp248,000 gp
251,640,000 XP138,000 gp208,000 gp312,000 gp

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.