Modrons in 5e: Full Guide – Lore, Abilities, Background

Last Updated on January 22, 2023

Of all the weird, wacky creatures WotC has come up with, one of my favorites definitely has to be the Modrons.

These little constructs are just so strange that they’re worth reading about even if you never plan on using them in a campaign. 

Today’s article is all about the mechanical inhabitants of Mechanus. From the Great Modron March to Primus (not the band) there’s a lot to cover, so let’s jump in.

What Are Modrons?

Modrons are perhaps the most lawful beings in all of D&D. They are a subset of constructs native to the lawful neutral plane of Mechanus.

These strange creatures are responsible for the clockwork operation of the plane, and they do so with absolute efficiency.

There isn’t a single creature called a modron; rather, this is the name given to a large variety of similar constructs created by Primus, the godlike ruler of Mechanus.

Modrons are split into 14 castes, ranging from monodrones to secundus. 

Modrons all follow the directions of Primus in an effort to uphold order throughout the multiverse. How they do this… isn’t exactly clear.

We do know that their understanding of the laws of the multiverse far exceeds the comprehension of any mortal. I guess that goes for us here in the real world as well.

These creatures make the most sense when thought of as extensions of the many gears of Mechanus.

For those of you that don’t know, Mechanus is a plane also called Nirvana at times. It is, as a plane, the perfect representation of lawfulness and balance.

It exists as an infinite number of interlocking gears. Its clockwork nature is tended by the modrons and reflected in them as well.

Modron Society

Modrons adhere to a very simple societal construct. Since they exist only to serve the purpose given to them by Primus (to uphold lawfulness), they don’t need to do anything other than follow orders.

In doing so, modrons follow the orders of any higher-ranking modron. 

This is where it gets exciting. Modrons are split into 14 castes, existing within two categories. The first category can be thought of as the worker bees, while the second is the ruling class.

Even then, ruling class doesn’t exactly fit it, because these all still exist to serve Primus. Even Primus himself exists only to uphold lawfulness. 

So what are the different types of Modrons?

Before we get into the deeper explanations, I’ve put them into these neat tables for you.

Base

Heirarch

With monodrones being the most common and secundus the least common, this hierarchy actually leads all the way to the top.

Primus himself is actually the highest rank of modron. If Primus was to die, he would be replaced by a secundus.

This “rule of replacement” goes all the way back down. If any modron dies, it disintegrates. At the same time, a modron of the next lowest rank immediately transforms, taking on the new rank and replacing the fallen modron.

This happens all the way down to monodrones. To replace the promoted monodrone, Primus simply creates a new one. 

This simple system keeps things running incredibly smoothly, even if Primus is the only one actually aware of it happening.

Modrons don’t actually understand any other modrons further than one rank a part. They are simply part of the system; they don’t need to understand it. 

For example, a quadrone is aware of pentadrones and tridrones. If they were to see a duodrone, they would just assume it was a particularly weak tridrone.

The same sort of concept fits into how modrons order each other around.

Modrons take orders from higher ranks and give orders to lower ranks, even if they might be a bit confused on the complexity of it all. 

Types of Modrons

Modrons are real creatures you can bump into, so of course, we’re going to take you through them. This list does only include solid information up to pentadrones.

Unfortunately, we don’t have stat blocks on the more powerful modrons in the hierarchy, at least in 5e. Everything else is information we’ve pulled from earlier editions.

To make it a bit easier to read through, below I’ve pulled out a couple of abilities from the stat blocks. Both of the following abilities are present in every modron.

• Axiomatic Mind. The monodrone can’t be compelled to act in a manner contrary to its nature or its instructions. 
• Disintegration. If the monodrone dies, its body disintegrates into dust, leaving behind its weapons and anything else it was carrying.

The only thing that can change this would be a rogue modron.

Rogue modrons, for whatever reason, abandon their duties and responsibility to uphold order. Because of this, they no longer gain the benefits of the Axiomatic Mind ability. 

Monodrone

Monodrones are the lowest rung of modron society. As such, they are created by Primus rather than being transformed through promotion.

Like simple computers, monodrones can only perform one simple task at a time or relay a single message of up to 48 words.

Monodrones are spherical constructs, with a single eye taking up the majority of their face/body. They have two arms, two wings, and two legs.

Duodrone

Duodrones are a stack of two blocks connected by a gear and spring. They do not have wings, but they do have two eyes.

These modrons command a unit of monodrones, and can perform up to two tasks at a time.

Tridrone

Tridrones are inverted pyramids with a face, arm, and a set of legs on each triangular side.

These modrons naturally order around groups of duodrones but are also commonly used as the commanders whenever modrons find themselves in battle. 

Quadrone

Quadrones again come with wings, and are essentially very agile and skilled cubes. These are the field officers of modron military regiments.

Pentadrone

Pentadrones are the weirdest, most organic-looking modrons out there. They are essentially a semi-organic, semi-robotic starfish propped up on five legs. On each arm of the starfish-like body is a face.

Weirdness aside, pentadrones are also the first in the hierarchy of modrons to be able to improvise and respond to situations as they arise.

More than merely followers, they can act in ways beyond what they are ordered to do but not beyond how they are programmed. 

Heirarch Modrons

Heirarch modrons have all had spellcasting abilities in earlier editions of D&D.

This would include spells like teleport, wall of force, clairvoyance, dimension door, and command. Similar spells would make plenty of sense if you planned to include any of these in a campaign. 

The different ranks had access to different types of spells in addition to these.

Decatons could cast healing spells. Nonatons could cast psionic spells. Octons and quintons cast divine spells associated with Order, War, and Peace domains.

Septons, hextons, and tertians can cast most wizard and sorcerer spells. Secundus could cast most spells cast by any lower modrons.

The heirarch modrons have all been described in various ways across different editions.

The key points to remember when describing any of these is the number they are associated with and that modrons look weird.

The higher in ranking they get, the more strangely biological they should look, with Primus almost appearing to be of a humanoid shape. 

The Great Modron March

Every 289 years, when the gears of mechanus complete 17 cycles, Primus sends a great army through the Outer Planes of the multiverse. Why exactly this was done, no one really knows.

There isn’t much to talk about this, but it’s an interesting piece of lore that I just couldn’t skip out on. The march is described as incredibly dangerous, with sometimes only a few modrons returning out of the thousands that depart.

All signs point to the march being a sort of reconnaissance mission, but considering that the modrons never stop at any locations or talk with anyone along the trip, even that doesn’t quite make sense. 

There was one time, an adventure in 2e, when the modrons marched outside of their schedule.

Spoiler Alert. I feel like a spoiler for a 25-year-old adventure module is weird, but I care about you guys enough to not ruin it in case your DM has plans.

Anyways, the modrons were searching for the Wand of Orcus after the demon lord slayed Primus. Fun story, very interesting adventure that takes you through several planes.

Modrons are weird constructs. Adherent to absolute law and efficiency, they really are one of the strangest things you might come across in D&D, and that’s definitely saying something.

I hope you have the fortune of coming across them in your travels.

And as always, happy adventuring.