Creating Monsters

Overview

To create a unique monster, follow these steps:

Roll on the Monster Appearance table.
Roll on the Monster Traits table.
Roll on the Monster Attacks table.
Roll on the Monster Abilities table.
Describe the creature’s appearance, abilities, and attacks in plain English.
Create the creature’s stats according to the principles, definitions, and stat block format below.

Principles

Use Critical Damage to lean into the threat or strangeness of any aggressive NPC.
Use flavor and style to help creatures stand out. Players will remember a pig-faced humanoid looking for his missing sheep more easily than a generic goblin archer.
Always adjust creature stats based on what is fun and interesting.

Hit Protection

A creature’s ability to avoid danger, whether through toughness, speed, or skill. Give average creatures 3 HP, give hardier ones 6 HP, and and give serious threats 10 or higher.

Armor

For some creatures, this represents their natural toughness; for others, it may be from something that is worn or carried. If a creature is able to withstand an attack without moving, raise this number.

Ability Score

3 is deficient, 6 is weak, 10 is average, 14 is noteworthy, and 18 is legendary.

Strength

Tracks overall health, physical power, and resistance to poisons. It is the ability of a creature to survive a direct hit, not its ability to avoid danger!

Dexterity

Start with 10 as a base, and if the creature is particularly quick, agile, or nimble, increase the number as necessary. If it is slow to respond, bulky, or clumsy, lower the number.

Willpower

Determines a creature’s ability to withstand the influence of another, as well as their power over others. It also acts as a measurement of their defense in magical or spiritual matters.

Attacks

Typically an object (e.g. sword or bow) or a natural weapon (e.g. claws or teeth).

Abilities

A unique action or power the creature can utilize both in and out of combat.

If an ability can be meaningfully avoided or defended against through traditional means, it is an Attack and interacts with HP.
If an ability cannot be meaningfully avoided or defended against through traditional means, it is an Ability.
If an ability only affects a single PC, it should generally have an immediate effect with no chance to Save in that round (possibly not at all).
If an ability is capable of affecting a group of PCs, it should generally call for an immediate Save.

Monster Stat Block Format

X HP, X Armor, X STR, X DEX, X WIL, Attack (dX, special items, qualities)

An engaging descriptor of appearance, demeanor, or living habits.
A quirk, tactic, or peculiarity that distinguish this creature.
Special effect or consequence of critical damage.

Monster Appearance

Roll 1d20 for each column and combine the results.


d20	Physique	Feature
1	Albino	Antennae
2	Black	Beak
3	Crystalline	Carapace
4	Emaciated	Claws
5	Eyeless	Fangs
6	Feathered	Feathers
7	Gelatinous	Fur
8	Glowing	Gilled
9	Hardened	Horns
10	Headless	Markings
11	Horned	Scales
12	Hunched	Shell
13	Iridescent	Snout
14	Polyocular	Tail
15	Scaled	Talons
16	Segmented	Tentacles
17	Skeletal	Trunk
18	Slimy	Tusks
19	Translucent	Voice
20	Twisted	Wings

Monster Traits

Roll 1d20 for each column and combine the results.


d20	Quirks	Weakness
1	Alters Its Size at Will	Alcohol
2	Changes Color at Will	Cold
3	Collects Rare Flowers	Conversation
4	Collects Trophies	Flattery
5	Does Not Die of Old Age	Games
6	Draws Symbols	Gifts
7	Fascinated by Fire	Iron
8	Hoards Books	Loud Noises
9	Loves a Specific Color	Mirrors
10	Reborn Each Day	Bright Colors
11	Loves Shiny Objects	Moonlight
12	Mimics Voices	Music
13	Moves in a Straight Line	Prepared Meals
14	Narrates Everything	Puzzles
15	Obsessively Cleans	Religious Icons
16	Plants Grow in Its Wake	Salt
17	Sleeps Upside Down	Silver
18	Speaks in Rhymes	Sunlight
19	Sweats Rare Minerals	True Name
20	Reproduces Asexually	Weak Spot

Monster Attacks


d20	Type	Critical Damage
1	Bites	Asphyxiates
2	Blunts	Bleeds
3	Burns	Blinds
4	Freezes	Breaks
5	Gases	Crushes
6	Kicks	Decays
7	Punches	Dissolves
8	Shoots	Ensnares
9	Slams	Explodes
10	Slashes	Grapples
11	Slices	Incapacitates
12	Smashes	Lacerates
13	Sprays	Liquefies
14	Squeezes	Paralyzes
15	Stabs	Petrifies
16	Stings	Poisons
17	Throws	Punctures
18	Touches	Severs
19	Whips	Tramples
20	Zaps	Weakens

Monster Abilities

Roll 1d20 for each column and combine the results.


d20	Ability	Target
1	Absorbs	Body
3	Amplifies	Dreams
4	Attracts	Element
5	Binds	Emotions
6	Camouflages	Energy
7	Conjures	Health
8	Controls	Hearing
9	Disables	Illusions
11	Duplicates	Light
12	Grows	Memory
13	Manipulates	Metal
14	Reflects	Plants
15	Regenerates	Spirit
2	Resists	Stone
16	Reverses	Surroundings
17	Shapes	Time
18	Shrinks	Vision
19	Transforms	Water
20	Traps	Weather

Monster Example

Appearance: Hunched + Carapace.
Traits: Moves in a straight line + Weak Spot
Attack: Smashes + Grapples.
Abilities: Disables + Hearing

A snail-like creature with a hard shell. It moves only in straight lines, and has a soft underbelly. It rolls into opponents, pulling them into its wild orbit. The roar of its movement drowns out any other sounds.

This creature is physically tough, with higher than average STR and strong armor. It is probably fast but not maneuverable, and likely doesn’t rely on skill or dexterity to avoid danger. It is brutish, but it is still a wild beast and only as willful as any creature just looking for its next meal. It attacks by rolling in a straight line and should impact multiple targets.

Thunder Snail

6 HP, 2 Armor, 14 STR, 6 DEX, 4 WIL, smash & roll (d10, blast)

Thick-shelled beasts that attack by rolling over their opponents in a straight line. The noise of their tumbling shells is deafening.
Critical Damage: Target is pulled into its rolling momentum, losing an additional 1 STR per round until freed (STR save to escape).

Converting Monsters

There is no perfect system for converting from other systems. Here are some tips that might help with the process!

Hit Protection: A good rule of thumb is to give the creature +1 HP for every HD, on top of a minimum 3 HP (the average person). I usually think of HD as equivalent to a d6, which has a mean of 3.5. Always start with a creature’s HP first, then do their STR.
Armor: Look for phrases like “as leather” and “as plate” in the original stat blocks. When converting from B/X style games like Old School Essentials, ignore THAC0 and use descending AC whenever possible (7 = Leather, 5 = Chainmail, 3 = Plate mail). If only ascending AC is given, you can use (12 = Leather, 14 = Chainmail, 16 = Plate mail). Whichever system you’re converting from, the Armor values range from 1-3 only.
Strength: Look at the creature’s HD and HP. If a creature is difficult to kill but not because they are nimble or skilled, give them more STR (but not more HP). Start with 10 STR (the average) and go up or down from there.
Dexterity: Start with 10 as a base, and if the creature is particularly quick (often referred to as “speed” or SP), agile, or nimble-fingered, raise the number. If it is slow to respond, bulky, or clumsy, lower the number. See Saving Throws below for more!
Willpower: Morale (ML) can be a good guidepost, and it typically ranges between 2-12. The greater the creature’s personality, spirit, or presence, the higher the WIL they should have. The following table offers a decent guide on converting ML to WIL.


ML	4	8	10	12
WIL	6	12	15	18

Saving Throws

You can rely on saving throws to glean more information about a creature’s abilities, specifically their ability to avoid death by physical trauma, magic, or poison.
Stat blocks will use a shorthand like (E1) or (F1) (Level 1 Elf or Fighter respectively). These are really helpful for quickly identifying the creature’s abilities.
Consider adding descriptive tags such as “immune to toxic gas” or “good at dodging” based on the saving throws. The following table should help determine which saving throws should result in an increase in one of the relevant ability scores.


Death or Poison	STR
Wands	DEX
Paralysis or Petrification	WIL or STR
Breath Attacks	DEX or STR
Spells, Rods or Staves	WIL

Combat

Damage Die: Can typically be copied “as is” from most OSR systems, but it’s a good idea to check with the weapons listed in the Marketplace first.
Multiple attacks: Convert to blast or to multiple dice (e.g. d6+d6).
Devastating Attacks: Consider making the damage enhanced, assign the blast tag, or giving the attack multiple dice.

Abilities

Sometimes the mechanics of the original system simply do not translate. That’s OK! Try to focus on what’s most interesting about the creature, and write a “version” of their ability more appropriate to Cairn.
Abilities can sometimes be made into attacks (with a damage die), leaving Critical Damage to reveal the real impact.
If the monster has an attack that asks the PCs to attempt to dodge or save against some ability, consider making the ability an out-of-combat “trap” that the PCs can trigger. Otherwise, make it succeed automatically. Combat is dangerous, and it is up to the Warden to properly telegraph danger before the fighting begins.

Magic

Magical creatures can “know” a bunch of spells without needing to carry Spellbooks. In this case, make their corpses magical (and dangerous)!
Spells are tricky; you can give magic-users Spellbooks, but remember, they might drop them when defeated.
Consider making some of the dropped Spellbooks implode (use the Die of Fate to determine which).

Use the Fiction

The easiest way to convert a monster from another system is to read the original stat block and any associated text, then write a few sentences about the creature in plain English. Finally, convert what you’ve written to the Cairn monster stat block.

Take for example this creature:

Foxwoman

Can take the form of a fox or a 7’ tall fox-headed woman. HD 5, Speed 120’, Armor 14, Morale 11, Attack: +4 d8hp (claw, bite or choke)

Defense: Cannot be harmed by metal
Special: Can transform into a fox or a maiden with one fox leg hidden (same stats) at will

Using the example above, I can see that she:

She appears as a 7-foot tall human woman with the leg of a fox.
She doesn’t have super high HP, and she’s quite fast.
Her ML is pretty high, and she’s obviously quite willful.
She is agile and lithe.
She attacks with teeth and claws (choking her prey if possible).
She can transform into a fox at will.
She is immune to metal weapons.

What can we learn from this?

She’s fast, and probably savvy in a fight. If we start from 3 HP and add 1 HP per HD, that means she has 8 HP.
I don’t think foxes have protective hides, and she’s otherwise human beside her head. No Armor.
She is decently strong. A normal human has 10 STR and she’s a little bigger. 12 STR.
I can imagine her hunting prey over the snowy tundra. She’s fast. 14 DEX.
Her ML is high, and foxes are known for their cunning. 15 WIL.
For her attacks, I’d go with claws (d6+d6) and bite (d8).

This information leaves us with the following: 8 HP, 12 STR, 14 DEX, 15 WIL, claws (d6+d6), bite (d8)

Now on to her abilities: This is pretty straightforward. We simply read the fictional stat block we created earlier!

She appears as a 7-foot tall human woman with the head of a fox.
She can transforms into a fox at will.
She is immune to attacks from metal weapons.
She chokes her victims into unconsciousness.

The final result:

Foxwoman

8 HP, 12 STR, 14 DEX, 15 WIL, claws (d6+d6), bite (d8)

Can take the form of a fox or a woman with a hidden fox leg.
Immune to attacks from metal weapons.
Critical damage: Victim is choked unconscious.