If you have played Dm`ed Pathfinder, we are 100% sure you wanted to make the party fight an enemy that you couldn’t find on the bestiary: that`s how the creation of custom monsters comes into play. Have your party ever fought Davy Jones and his crew on the Flying Dutchman? Have you ever had a chance to ride Toothless from “Dragon Trainer”?

With this guide, we will help you create your personal bestiary and spice up your encounters.

We will provide links for every source you need at the end of the page.

GUIDE FOR YOUR PERSONAL BESTIARY

First steps

1. Choose your creature, think about what you want it to do, and think about its personality and behavior. Then you can start by writing its name and its general descriptions. That will help you by setting a general guideline.
2. Assign its alignment.
3. Assign its size. Remember that for later, it will affect some stats in this way:

• Petite: AC:+3 Base atk:+3 Base STR:1 Base DEX:16 Base CON:8
• Tiny: AC:+2 Base atk:+2 Base STR: 2 Base DEX: 14 Base CON: 8
• Small: AC:+1 Base atk:+1 Base STR: 6 Base DEX: 12 Base CON: 8
• Medium: AC:+0 Base atk:+0 Base STR: 10 Base DEX: 10 Base CON: 10
• Large: AC:-1 Base atk:-1 Base STR: 18 Base DEX: 8 Base CON: 14
• Huge: AC:-2 Base atk:-2 Base STR: 26 Base DEX: 6 Base CON: 18
• Gargantuan: AC:-3 Base atk:-3 Base STR: 34 Base DEX: 6 Base CON: 22
• Colossal: AC:-4 Base atk:-4 Base STR: 42 Base DEX: 6 Base CON: 26

Assign its category and subcategory. Watch out, some of these can give some special traits to a creature, For Example: Undead creatures are immune to non-lethal attacks.

Size	Space	Example
Tiny	0.5 by 0.5 m	Imp, Sprite
Small	1.5 by 1.5 m	Giant rat, goblin
Medium	1.5 by 1.5 m	Orc, Werewolf
Large	3 by 3 m	Hippogriff, Ogre
Huge	4.5 by 4.5 m	Fire giant, Treant
Gargantuan	6 by 6 m (or larger)	Kraken or Purple Worm

Stats (and boring stuff)

1. Determine how many HP (Health Points) will your creature have in this way: Choose the number of life dice it will have. The creature’s category determines the type of the dice.
2. Assign its stats (STR, DEX, CON, INT, WIS, CHA). We advise you to take inspiration from similar already existing creatures and to choose if you want to apply the previous base stats or not.
3. Now that you have its stats, calculate the initiative modifier, the init. the modifier is equal to the DEX modifier.
4. Calculate its base atk. You have to determine how much your creature is capable of handling a physical fight
   – If your creature likely uses brute force in its behavior, its base atk is equal to the amount of life dices that it has.
   – If your creature is frail or weak its base atk is equal to half its life dices (rounding down)
   These are, however, guidelines, not rigid constraints; so feel free to modify them according to your project.
   Remember to add or subtract the size modifier.
5. Calculate its CMB and its CMD.
   CMB=Base_atk+mod_STR
   CMD=10+Base_atk+mod_STR+mod_DEX
6. Assign some of its abilities (the most relevant ones).

How to calculate the Hit Points (Health Points) according to size

Size	Hit Die	Average HP per DIE
Tiny	d4	2 ½
Small	d6	3 ½
Medium	d8	4 ½
Large	d10	5 ½
Huge	d12	6 ½
Gargantuan	d20	10 ½

Saving Throw Bonuses

SAVING THROW BONUSES = monster’s relevant ability modifier + Proficiency bonus
Proficiency Bonus – It is a bonus that has to be added as a modifier to the saving throw bonuses.It depends to the Challenge rating of the creature

Challenge	Proficiency Bonus	Challenge	Proficiency Bonus
0	+2	14	+5
⅛	+2	15	+5
¼	+2	16	+5
½	+2	17	+6
1	+2	18	+6
2	+2	19	+6
3	+2	20	+6
4	+2	21	+7
5	+3	22	+7
6	+3	23	+7
7	+3	24	+7
8	+3	25	+8
9	+4	26	+8
10	+4	27	+8
11	+4	28	+8
12	+4	29	+9
13	+5	30	+9

Defence

1. Calculate its armor class. AC is calculated in this way:
   AC=10+mod_DEX+Natural_Armour+Armour_Bonuses+Dodge
   Natural and artificial armor bonuses are defined by you.
   To calculate the touch AC you have to subtract armor bonuses.
   To calculate the flat-footed AC instead, you have to subtract the DEX modifier and dodge.
2. Calculate the saving throws. For each type of saving throw, you have to determine if your creature is able to withstand physical fatigue, react to sudden danger, or maintain its mental sanity.
   – If you creature is able in that type, its base stat will be equal to half of its life dices +2
   – If not the base stat will be equal to the amount of live dices divided by 3 (rounding down)
   Now that you have the three base stats, add the correct modifier:
   Fort=Base+mod_CON
   Ref=Base+mod_DEX
   Will=Base+mod_WIS
3. Determine immunities, damage reductions, and elemental and spell resistances as you wish.

Make your custom creature ready for battle

1. Define ranged and melee attacks, including much details as you can, so you can easily find all the information you need when the creature is attacking. Referring to the example sheet, fill the marked names/parameters as you wish, remember though that attack and damage bonuses are given by the previous calculations.
   If your creature uses a weapon, parameters like crit. range/multiplier and damage are given by that weapon.
2. Define the amount of space that your creature occupies, accordingly to its size.
3. Define its melee standard reach accordingly to its size as well. If your creature has a tail or a spear, that has a longer reach, specify that between parenthesis.
4. If your creature is magic, probably it can cast some spells. You must define its caster level; that will determine the maximum level of its spells and their power. You also have to calculate its concentration bonus: concentration=Caster_level+mod.
   The modifier used in the formula is defined by the stat that your creature rely on to cast spells. Clerics and devils use charisma, wizards and mages use intelligence, druids and witches use wisdom.
   Note: a permanent spell is always active while if a spell can be used at will it means only that it can be used many times as you like.
   Other spells have limited charges, so you must specify how many times a specific spell can be casted in the same day.
5. Set the creature speed/speeds.

A few decisions to make

1. If you want your creature to have some kind of aura, you can specify the details: name, radius, DC for the saving throw and we advise you to describe it as well.
2. In the “senses” slot you can put the ability modifier for perception, so it’s easier to find in game.
3. Specify the languages it can speak, or if it uses telepathy.
4. Add some feats and update your sheet accordingly to that.
5. If you want, add special qualities, defensive abilities and special attacks. these are totally customizable and as long that you describe what they do, you can write whatever you want.
6. Describe in which biome or environment your creature is expected to be found.
7. Determine its organization by describing if usually it’s a solitary creature or if many of them move in packs or in clans, or form a society.
8. If you want you can specify what rewards belong to an adventurer that will slay this creature. You can also customize the amount of XP gained from killing it.

EXPERIENCE POINTS

It briefly measure how much the monster is measured: it based according to the challenge rating.

Challenge	Proficiency Bonus	Challenge	Proficiency Bonus
0	+2	14	+5
⅛	+2	15	+5
¼	+2	16	+5
½	+2	17	+6
1	+2	18	+6
2	+2	19	+6
3	+2	20	+6
4	+2	21	+7
5	+3	22	+7
6	+3	23	+7
7	+3	24	+7
8	+3	25	+8
9	+4	26	+8
10	+4	27	+8
11	+4	28	+8
12	+4	29	+9
13	+5	30	+9

AND FINALLY… CR!

You’re probably asking why we are putting the CR at the end of the list. Well, CR is not a precise parameter.

To make it simple you can say that CR equals life dices.

But the true meaning of CR is: “This creature can give trouble to a small party ( 2-3 players) of level X” in which “X” is equal to the CR of your creature.

So to better define it you should simulate a battle against three or four dummies of level X and see how well it performs. If it annihilates the dummies you should give it an higher CR. If it can’t even scratch the armour of the dummies, maybe you overestimate its power, so you should lower the CR.

CREDITS

• Read more about the myth of the  Sleipnir
• Discover the Sleipnir in DnD 5e (SRD 5e)
• Cover Artwork by Michael Kutsche
• Artwork by Tey Bartolome