Spherical monodrone, rectagular duodrome, pyramid tridrome, cubic quadrome, star-shaped pentadrome

Monster of the Week: Modrons


What the heck is a modron?

I’m so glad you asked.

Modrons are a type of Dungeons and Dragons monster that have been around since AD&D’s first edition – over thirty years, now. They’re clockwork constructs made of both organic and mechanical parts. They’re weird, they’re cute, they’re sort of steampunk, and they’ll kick your ass at calculus.

The interesting thing about modrons is that I can’t just show you a picture of what the average modron looks like. There are many different types of modrons, each with its own look and function. Think of it like this: where corgis, chihuauas, and huskies are all types of dogs, you have monodrones, duodrones, and a whole bunch of others that are all modrons.

Why is this interesting?

Well, those of you who have brushed up on your Latin roots may have noticed a pattern in the names up there. If you learn one thing from this post, it should be that modrons are organized.

Specifically, they’re organized into fifteen different castes. At the very bottom, you have monodrones, duodrones, tridrones, quadrones, and pentadrones. Each of these types increases in rank, intelligence, and shape as they go up. So, a monodrone looks like a sphere with one big eye and some spindly little limbs. Duodrones are rectangles. Tridrones? Pyramids. And so on.

Yeah. They’re really into math.

In fact, they’re so into math that their entire language is based on it. And the monodrones – who are the most numerous – can’t even speak the common tongue, so they just kind of putter around sounding like numbers stations.

So what about the other ten castes?

Those ranks are special – they’re called hierarch modrons. Starting from the least important and most numerous, we have decatons, then nonatons, octatons, and so on, all the way down to Primus – the ruler of all modrons.

Okay, so they’re really into math and hierarchy. So what?

Oh, man, I’ve barely even scratched the surface of their obsession with order. Seriously – they live on the Plane of Law, which is called Mechanus, and call their city Regulus. They each have a specific purpose prescribed by their rank in society – and all members of that rank are not only equal but interchangeable. They don’t even refer to themselves in the first person singular because they have no concept of an individual: there is only we, all modrons. They’re literally cogs in a machine.

Their slavish devotion to the laws of mathematics also extends to the laws of their hierarchy. Each monodrone reports to a duodrone, each duodrone to a tridrone, and so on. It follows any order from its direct supervisor without question.

Here’s where it gets really interesting, though – a modron can only take orders from its direct supervisor. It can’t even fathom the existence of modrons further up the chain. And while it understands that modrons beneath it exist, it’s not allowed to communicate with them. Modrons can only communicate with the castes directly above and below their own.


It could just be their innate love of order. But why their society came to be organized in this way could be because of rogue modrons.

Yeah, I know, modrons don’t really seem the type to go rogue, do they? Everybody seems to have a renegade drow player character somewhere, but I’m willing to bet very few D&D players have sat down at a table with a modron.

(Well, maybe more of us would if there were rules for modron player characters post-2nd edition – but I digress….)

Occasionally a modron will go defective and begin to develop self-awareness. Most of modron law enforcement is dedicated to hunting down and eliminating these rogues. Their innate devotion to logic and order keeps modrons from intentionally rebelling against the system, but receiving conflicting orders could create an error in their internal logic. It’s likely that their communication rules came about as a way to limit errors like these.

When a modron dies, it… well, it doesn’t really die. Its body will be destroyed, sure, but its soul goes back to a pool of life force back on Regulus. All modron life spawns from this pool, where Primus lives. In order to satisfy their rules of law and order, a new modron must be created – its body will come from an existing monodrone, which replicates itself like a cell, and its soul comes out of the communal life force pool. If a high-level modron dies, the nearest modron from the level beneath it will get promoted.

As if they weren’t math-y enough, there must always be the same number of modrons in existence, and that number varies by caste – there is one Primus, four (two squared) secundi, nine (three squared) tertians, and so on. Cute, right?

… Right? I can’t be the only one who thinks math is cute? Oh, no. My pocket protector is showing.

So what makes modrons monsters, other than the fact that they’re in the Monster Manual?

I wouldn’t say that modrons are inherently monstrous. They just follow the rules of the system that they live in, a system that exists without concern for human life or its values of good and evil. Sometimes, modrons can be helpful – they’ll help clean up and organize. A wizard might hire a modron as a librarian, for example.

Other times….

Well, why don’t you ask that rogue modron how it feels about getting exterminated? Or any other living being that happens to defy a modron’s sense of how an orderly word should be?

Modrons are certainly capable of monstrous actions – even if they wouldn’t see it that way. They don’t have a concept of monstrous, just disorderly. They’re a cautionary tale of what can come from obeying arbitrary rules without thinking critically about whether or not they’re good rules.

Of just following orders.

So keep that in mind next time your lawful stupid paladin comes out to play.

Thoughts on modrons? I have a soft spot for these weird little mechanical guys, but they’re not your garden-variety Tolkienien creatures. Share your thoughts!


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