GRENDEL MENDEL: Using Punnett Squares For Monster Design

Swine Chopper
from Darkest Dungeons

Once again I am surprised by what catches fire on Twitter and what doesn't. The most recent example is a response I posted to Luke Gearing and Sean McCoy's tweets about simple monster design. I agree with both in that it shouldn't be too complicated, but you do need some variation. To achieve that, I use a sort of "Punnett's square" based on [melee or range] x [dmg or special]. 

I created this method when trying to figure our how to further differentiate all the various factions in Forbidden Caverns of Archia. This megadungeon module has several factions that players interact with and I wanted to given them both a distinctive feel and strategic/tactical pros and cons. That way PCs could make informed decisions, based on their own party compositions, of who to interact with and tactics to use.

Here the basic Punnett's Square outline and below I will explain (1) how I envision each quadrant, (2) how this tool can be scaled to a small force, a singular "boss" monster, or a whole dungeon level, and (3) provide some examples.

The very basic square &
you most likely get it already.

I. Characteristics Of Each Quadrant

  • melee x damage: Enemies are characterized by how much damage they inflict and the melee weapons they use to do it: sword, axe, mace, or claws. The rank and file of an army or faction. The very basic unit.

    Generally I keep the damage to whatever weapon you use to define the melee "class". If in your game weapons have different qualities, such as in Luke Gearing's Wolves Upon the Coast, all the better. This might also be a could place to add an additional attack.

  • melee x special: For the exercise, I try to keep the damage at a 1d6 level but try to think of either (1) some unique way to deliver damage; (2) some unique effect on a successful melee hit in addition to the damage (which is why its kept low); (3) some spell-like effect that changes things while in melee. This quadrant might also include "attack animals" the (melee x damage) units might use.

    Now, since you are often running monsters in aggregate, I'd stick to just *one* additional effect and at the most two. This is because too many effects takes up DM brain-space.

    • Too quick!: Creature always attacks before PC
    • Charge: Creature moves in a straight-line anyone in between Save vs. Paralysis or take 1d6
    • Heavy hands: On a successful hit, save vs. paralysis or PC is knocked prone
    • Duelist: On a dmg roll of 1, save vs. paralysis or PC has weapon knocked from hand (may choose shield)
    • Grisly visage: Creaure has a 5' aura of fear
    • Mirrored image: Hard to focus on the true creature, first X attacks automatically miss
    • Trog stench: Foul stench makes it hard to hit
    • Spiky: Take 1 damage per round engaged in melee with the creature (pretty classic)
    • Web: Creature entangle on a successful melee (also pretty classic)
  • range x damage: Another basic rank-and-file unit armed with missile weapons. I also include reach weapons in this quadrant like the ever-useful spear. Other mundane sources of missile fire could be the old oil+torch or flaming arrows. Or it could be (melee X damage) units that first engage with 1 or 2 javelins before pulling out swords.

    For a touch more flavor, I might also just put very basic magic-users here with magic-missile-like attacks or ranged elemental damage. Could also be interesting reach weapons like a giant scorpion tail whip.

    For the armor of these units, I drop it 1 or 2 points below the (melee X damage) units and also give them a 1d4 melee weapon of last resort. However, if you wanted to express that what players are facing is a well-run military machine, these (range x damage) might just convert into (melee x damage) once the distance is closed.

  • range x special: When filling out this quadrant, I often don't even think about damage at all (but I don't exclude it). I am often trying to come up with fun, interesting, and thematic area effects (mundane or magical). And creatures with more spell-like effects that give boons and/or banes to friend and foe alike.


    • Fetid air: A creature carries a censer that casts fog or darkness
    • Standard bearer: A unit carries a banner that carries a magical effect or boosts morale
    • Dance of the dead: A creature can raise any dead on the battlefield or beats a drum that causes the dead to rise on a 5:6 every round
    • Anti-magic eye: a creature has a Beholder central eye on a stick directed toward magic-users
    • Spider climb archers: creature can climb walls/ceiling and fire from there
    • Shadow hands: The unit produces large, but clumsy hands from the corner shadows to grab
II. Scaling for different situations

At the basic level, I created this tool to create small skirmish-sized bands to take on 4-6 PCs plus some hirelings- here is a square I completed for the kobold faction in Archaia. Mainly, I thought they might employ insects in the area and tried to do some effects around poison. The black shapes are just a little reminder about the relative ratio of the units to each other using d6's and d4's.

The punnett's square for kobold

But the above could also be put together to represent a single monster with multiple attack types. While it might seem like a lot of actions its not when you look at even an average 1st level party of PCs in aggregate. A 1st level BX D&D party (fighter, cleric, wizard, thief) is a 4 HD creature (~11 HP) that gets about 3 attacks per round, maybe 2 spells, and on the opportunity to have 1 attack deal 2x 1d6 damage. Look at our kobold block above, we could turn it into some sorta scorpion-like avatar of a kobold god. 

So this single opponent is characterized by:
  • melee x damage: 1d10 (pretty standard) but maybe the front half is better armored AC +2 
  • melee x special: Since 2x1d10 damage is already strong how about "if hit, can crush for 1d6 damage per round, STR to escape claw"
  • range x damage: Stinging tail with 10' reach
  • range x special :
    • (v1): Again, since we already have 3 attacks, how about "can throw PC hit with claw 15' 1d6 damage if they hit another PC or solid object
    • (v2): Summon a swarm of insects to surround any target in line of sight; 1:4 drop weapon or disrupt spell casting
ADDITIONAL LINK: I think this method is a different way to look at Matt Colville's "Action-Oriented Monsters".

We also scale in the opposite direction and use the four quadrants to represent a whole level of a dungeon or maybe as a way to seed four ideas that can be iterated around to fill out a 6 or 8 entry encounter table.

Why might we use this method as opposed to just listing some monsters? The main benefit is that is it helps us remember to infuse some variety into our monsters. And this doesn't just have to be so "combat" oriented. Our "special" categories could before monsters that steal items, spoil rations, or weird magical effects that permeate the dungeon. The end result hopefully is a list of monsters that reinforce the aesthetics of the dungeon but are heterogeneous enough that a heterogeneous PC party (because you are rolling 3d6 down-the-line right?) can make use of a lot of its members in various encounters.

ADDITIONAL LINK: Again, the Punnett's square method here I think provides a more "back-of-the-envelope" alternative to Gus L's Dungeon of Sign very excellent post about creating unique monsters. Pairs well with what each monster might want or its objective in combat other than killing everyone. Something I've written about here.

III. Example with different sources: standard D&D monster & video game

First up is skeletons. Always a classic because with the hand-waving powers of "necromancy" you can do just about anything with them. Often they are just relentlessly attacking 2-3 HP creatures dealing 1d4-1d6 damage. This is especially triesome as a hoard, so I used to matrix here to bring some suprises like the drummer which can raise fallen skeletons as well as many dead hirelings. And I also tried to answer the question, "How would something like elven skeleons work versus the often assume human ones?"

I really like the video game Darkest Dungeon eventhough I think the actual dungeon exploration portion could be better done. It does have a nice tacticle combat though. The creature design of the swine is especially evokative and perfect for use in the square. Nothing too suprising here, just trying to mix basic melee and ranged units with some specials that provide themed support.

With the Swine more than the Skeletons, maybe having weapon differentiation is more important. So the Swine have hooks. Does this mean they can rip sheilds aways or try to disarm? Swine also have javelins which could be barrbed dealing more damage? Or maybe create a deep wound? Maybe it better fits when them to lower all damage dice 1 step (so base 1d4) to enhance the improvised, rusted, and wicked nature of the weapons through an effect.

NIGHTWICK ABBEY: The Purple Eater of People, Session 9


Art by Chris Huth

Previously in Nightwick...

The Party

Blossom (Rogue 2)
Bertol (Rogue 2)
Mayfly (Magic-User 1)
Sumac (Changling 1)
Hirelings: None attending us this time

At the Medusa's Head...

(PC Note: This session was abbreviated, but revealed some good developments in terms of NPCs. And I think when attempting long-term campaigns, consistency of meeting, even briefly, trumps the length of any individual session.)

(PC Note: At the beginning of the session we also gained a new player!  With DEX 15, I believe another rogue. They will be joining us for Session 10- a milestone for sure!)

The date is Uno-December 13, 1390 and the feast of the new year has come and passed. But on this particular day, feasting of a different sort is occurring due to the wife of Nightwick Village, Lord Arkard, giving birth to a daughter.

But that is little of the party's concern. To be frank, Bertol was quite surprised Nightwick Village was large enough (or worthwhile enough) to garner governmental oversight of any sort. But this might have something to do with the proximity to Nightwick Abbey and the propensity of graveyards in the area to vomit forth their occupants.

The individual who occupied the party's, and specifically Mayfly's, attention was the noted magus of great power, Halfdan. A rumored man of great power and wicked nature. Mayfly thought he could sell the wineskin of bizarre blood to the mage to fund deeper exploration into Nightwick Abbey.

The party made their way down the road to the looming tower on the other side of the graveyard. On their approach, a surprising storm arose over the tower. Mayfly's eyes skittered over the front door, searching for any traps and finding none-- he knocked. And to his surprise, a bear answered.

The party was ushered, most politely, by the bear into a very old, musty (possibly lice-ridden) waiting area. The bear trundled upstairs and a few moments later the Magus Halfdan appeared. This supposedly great wizard called for drinks. Which was brought back down the stairs by the bear, holding mugs in its mouth and a cask of drink around its neck.

Discussion commenced with Mayfly angling to get payment for the weird blood. But after some back and froth, Halfdan was not forthcoming. Bertol stepped up to provide a shrewder way of putting things, resulting in a deal being put into place.

From Halfdan the party learned:

  • The blood is a type of trap. Using it (or ingesting it) will create a connection between the thing/person and Her (aka The Lady).
  • The Sword Brothers, builders of the Abbey, also had a fantastical underground garden and many wondrous contraptions. Halfdan will pay top dollar for them.
  • The Magus Halfdan gave the party a magic scroll in return for obtaining some items from the Abbey's garden within 6 months time.
  • The scroll: Read Magic (1st), Ventriloquism (1st), Fireball (3rd) [total value ~500 SP + 5 weeks to manufacture]
So fruitful! The party has obtained a "paper cannon" in the form of the fireball spell. And who knows Mayfly could transcribe the ventriloquism to his own spellbook (hmm...)

Pictures our DM used to capture
the "feel" of the NPCs


In the year 2020-too, I feel there are mortal hands plucking at the heartstrings of OD&D. Trying to see if the old body can rise anew? I think it's great! Understanding OD&D is most likely an important piece in the whole D&D puzzle not matter the edition you prefer.

Gus L. makes a good point in the Grognardia comments about the dangers of OD&D offloading a portion of the play experience to another game:

There's very little of the wilderness in D&D's wilderness and adventures in it have always felt more like a bus ride with occasional fistfights to me then hikes in wild places.

I suspect this can all be traced back to the decision to offload wilderness travel rules to Outdoor Survival (which after all is a one-shot board game with fairly frustrating rules - even worse when you add hostile bandit armies, dinosaurs, and dragons to it's already tough survival rules).

And finally, an astute Redditor makes a nice observation about OD&D's influence on why Moldvey Basic D&D stops at level 3: 

This stopping at level 3 intrigued me for a long while as well. Like, why three? 

Well .. level 4 is when in OD&D, in good and proper Chainmail fashion, your character graduates from being a normal (if aspiring) combatant to a proper Hero! This progression gets carried over, including the level titles from OD&D which itself includes the ones from Chainmail, into Holmes/Moldvay/B+X. 

Interestingly, many spells and effects only work on monsters/NPCs/etc up to 4HD(+1) ... because that's when things become Heroic. Chainmails "[Heroes] have the fighting ability of four figures" seems to have really set a major line in the sand.

CROSS-OVER EPISODE: My Review of The Hole In The Oak At Bones Of Contention


My Bones of Contention review of The Hole in The Oak covers how this might be a new low-level classic.

The actual play-through can be found here on this very blog.

If you are looking for a good adventure to start off the year with this is a good one. At the end of my players run through they were selling giant lizard eggs like gun runners.

NIGHTWICK ABBEY: The Purple Eater of People, Session 8


FIRST POST OF 2022: While I wanted to cap off 2021 by catching up to my Nightwick posts, I think it is only fitting that I start 2022 with a game I really look forward to every week and that I hope continues strong in the new year. This post also epitomizes what I want this blog to be about-- the *playing* of old-school games. The thoughts and principles of "classic play" when put into practice do work and yield engaging games.

In Nightwick previously...

The Party

Blossom (Rogue 1)
Bertol (Rogue 1)
Mayfly (Magic-User 1)
Sumac (Changling 1)- our first!
Hirelings: Red, Curly, Pavel, Assmus, Kunrat

(PC Note: Our DM, history expert, offered some great pre-game history facts that have, in part, informed the conception of Nightwick. This one involved a graduate from the famous school of Necromancy in Toledo Spain who was contacted by a bishop to summon the devil in order to cut some other Christian cult out of the miracle business. Its funny that despite being evil, it seems a lot of Church figures had the devil on speed dial.)

At the Medusa's Head...

Another two weeks pass since the last delve into Nightwick. The party has been mainly resting and trying to figure out how they will overcome the giant roadblock that is the Butcher of Nightwick. Review maps and plotting courses, the party decides to try to see what is on the second level of the dungeon. The rogues are feeling especially confident after perfecting their craft just a little bit more. So all is good except for the mysterious itch Blossom picked up after a long week of drinking...

(PC Note: So our Rogues leveled up by creeping ~100 XP over the line after some carousing. The thief class is often seen as weak in BX, but having the lowest progression, 1200 XP to go from 1st to 2nd, is quite meaningful when risking life and limb for every 100 GP. At the current rate, my MU Mayfly has to survive ~6-10 more delves to get to the 2nd level. This is not a knock against our DM nor old-school play mind you, but I think a demonstration of how XP differences among classes is a good constraint vs. 5e's unified progression.)

Nightwick, Right Tower, Level 2
(purple is recently explored)

A RAPID DESCENT TOWARDS 2nd LEVEL: With all haste, the party pushed into Nightwick's right tower and to the stairs located where four hanging bodies were found and the very nice silver bowls. Now replaced by wooden bowls-- the cheapskates.

FURTHER DEPICTIONS of THE LADY: At the bottom of the staircase were two columns each again depicting The Lady, prophetess of the Church of Law, in a lurid manner. However, for these columns, her eyes are hollowed out allowing a red fluid to drain out of them and pool below. North from the stairs is a single door.

A HALLWAY ENDING IN ABSOLUTE DARKNESS: After hearing nothing through the door, Blossom waves Red forward to due the honors of crowbarring the door open. Moving into the hallway our Chaingling Sumac takes point and reports the west direction terminates into absolute pitch blackness that even their dark vision does not penetrate, while the east contains two doors and extends further beyond the torchlight.

Mayfly is puzzled by the darkness, but before a solid theory about what it can be is formed based on years of academy training, Bertol sends one of the hirelings through. Without a rope tied to their waist. The hireling reports its really really dark and (amazingly) walks back out seemingly unscathed (sus -.-). Mayfly casts Light about 2 fit inside the darkness. Instead of eliminating it, the light seems to be surrounded by darkness. Two silver pieces later, another hireling walks through and reports it is just all white and too bright. With other avenues available the party decides to come back to it later.

BLOOD SCRIBBLING: Cautiously moving down the hall, the party checks the north door. Hearing nothing they quietly pop the door open and peer insights. One cultist is licking the red fluid off the wall, hood back, and feverishly whispering. A second cultist is on the ground apparently transcribing those words. The party quietly closes the door, but Mayfly thinks those writings might be very valuable.

A PACT OF DEVIL MEN: The party opens the door directly south and finds themselves face to face with four devil men! The party freezes in horror and anticipation of what might come next as they gaze upon the pointy horn and beards of this group-- three of which are virtually identical. The incongruous one speaks, "Clearly this is not a room you are invited into."  The party, "...uh..." and Bertol quietly closes the door.

And since both doors open inward, Sumac had the idea to tie them shut with a rope running between the pull rings ("---" above on the map). Might not hold forever, but certainly by the party time. Very clever.

BLOOD ORANGES: Not quite knowing what to make of all that, but knowing they still have empty pockets, the party turns north with Sumac bravely scouting in the dark. Sumac reports back there is a metal container (like a modern dumpster) set into the floor. In it are moldy orange peels. To the right of this container is a door and to the left, stairs leading down and a hallway continuing west.

The party checks out the door to the right and enters a room containing a large machine. A puddle of milky orange fluid on the ground. And five crates of bones and five crates of ...oranges?! Mayfly realizes that these are an incredibly valuable delicacy and certainly would fetch ~100 SP per crate! The party, experienced in knowin' when the gettin' is good, gathers up the oranges and absconds with them for a total haul of  500 SP . The biggest haul yet out of Nightwick.

...After a night's rest in Nightwick Village...

Bertol peeled off from the group, happy with his orange-tinted gains, but the rest of the party wanted to quickly go back to see if there was more to be purloined, especially from upper areas of the Abbey that had not been as well explored. This proved to be potentially a mistake...

Nightwick, Right Tower, Level 1
(purple is recently explored)

WE CAN'T STOP HERE, THIS IS (DEER-MEN) COUNTRY!: Entering the northeastern door, the party is brought up short by a goblin barricade. Mayfly tries a 2 SP bribe to see if the party can get any information about the stone vulture archway to the north. All they learn is that's where deer-men reside and the goblin don't go there.

Feeling bold, the party forms ranks with Red and Curly in front and march toward the archway. As they pass under the arch, Sumac spots a formation of deer-men and shortly after their bleating cries are heard! Their attack is swift! Arrows fly toward the party, several striking Red, dropping him, and severely wounding Curly. The party leaves Red's body behind in order to make sure they don't join him in repose.

Just before leaving, Sumac throws a few silver coins at the foot of the statues and notices that while the goblins want to grab them, they dare not move-- at least for that amount.

...back to The Medusa's Head.

Mayfly thinks it is time to visit this wizard "Half-Dan" and maybe brokering some information with the strange blood of the mixed-up beast he found in Nightwick.

 (PC Note: Well that last little bit did not go well at all. I think we certainly have reached a point where solid preparations will have to be made to move through Deer-man territory or make it past the Butcher. One advantage of all the map-making that has been done is that is easy to review where unexplored hallways and doors are. I think I need to draw everything together to see what options the party has. One of our new players also made a good risk assessment that the easiest stuff in Level 2 might still be less risky than the hardest stuff in Level 1.  So exploring Level 2 might be more worthwhile. Of course, there is always the Left Tower, but the hoards of deer-men there too pose a problem. Maybe it is time to sell a soul or something?