The Peasant Railgun: How to “Break” DnD 5e

Last Updated on January 22, 2023

Ever wanted to blow apart an enemy fortress in a single turn? How about melt an entire city? Kill a god? All these things (and much, much more) are possible with the focus of today’s guide: The Peasant Railgun. 

What is a Peasant Railgun? 

First, let’s break down exactly what a Peasant Railgun is before we get into all the reasons why it doesn’t work, isn’t allowed, and what we could accomplish if our DM actually let us build one – presumably we have incontrafutable evidence they’ve been fiddling their taxes and the IRS on speed dial. 

The Peasant Railgun is what happens when you mix a strict (read: selective) interpretation of the RAW and real-world physics. 

The results can range from comical to apocalyptic, and rely on a few key assumptions: 

1. In D&D 5e, a turn always takes 6 seconds. 
2. All creatures in the initiative order can act within a turn. 
3. Passing an object traveling at just over a thousand miles per hour with your bare hands doesn’t melt your hand off. 

Now, let’s meet the two conceptual components of the Peasant Railgun. 

Peasants

Perfectly average folk like this fellow here.

Of course, you don’t have to use peasants (some people argue that you need monks with the ability to Deflect Missiles in order not to melt people’s hands off) and any creature with the ability to lift about 7lbs (weight of a ten-foot pole) will do in a pinch. 

However, we’re going to need a lot of people to make this stupid idea work, and peasants are the cheapest, most readily available humanoid resource in most medieval-adjacent settings, so let’s go with them. 

A very large number of peasants (using the stats for Commoners in the Monster Manual) should be sufficient for our purposes. 

A Railgun 

An insanely powerful projectile weapon that uses electromagnetic force to accelerate an object very very quickly.

Modern militaries (the US Navy in particular) have been working on railguns for a number of years now, which have resulted in bonkers crap like this. 

Now, using a few thousand peasants (and a somewhat selective interpretation of the rules of physics) instead of electromagnets, we can create a weapon that’s capable of leveling mountains and turning an ancient red dragon into a fine mist on impact. 

What If We Made a Peasant Railgun… Bigger? 

Firing a ten-foot pole at just over a thousand miles per hour is great. But what if we wanted to turn things up a few million notches? 

I was thinking about a great thought experiment done by Randall Munroe (creator of xkcd) in his book What If… which answers what would happen if you tried to hit a baseball traveling at 90% of the speed of light. 

First, we’re going to need a much, much bigger railgun. 

If a 2-mile railgun composed of 2280 peasants produces a projectile traveling at 1180 miles per hour, in order to hit the speed of light (roughly 670,616,629 miles per hour, or over half a million times faster) we’re going to need 1,287,042,015 peasants. 

Assuming they’re all still standing 5ft apart, they need to be in a line that means our Peasant Railgun ends up being roughly 1,128,984 miles long. This means it would reach about 45 times round the earth or slightly further than the moon and back twice.

Now, you can snake the line back and forth like an airport check-in, but this endeavor is still going to take up a modestly sized kingdom. 

Then, there’s the question of cost. The rules of 5e state that unskilled hirelings cost 2 sp per day, so at minimum we’re going to need a cool quarter of a million gold to finance this (plus 1 silver piece for the ladder), which honestly feels kind of cheap for a gun that can kill god. 

Putting aside the fact that, if taking down an enemy is your goal, 1.2 million peasants would be put to much better use just walking up to the monster, castle, or god that you want dead and beating it to death with clubs, the FTL Peasant Railgun can produce some serious results. 

Going back to Randall Munroe’s article on Relative Baseball (and assuming that the ten-foot pole makes it to the front of the line before the laws of physics kick in), things get real bad, real fast. 

The pole is traveling too fast for the laws of fluid dynamics to move air around it. Instead, the air molecules are smashed apart by the pole, creating a near-instant nuclear fusion reaction.

Over the next 40 nanoseconds, the atomized fragments of pole and air molecules grow into a ball of plasma and nuclear fusion expanding outwards in all directions and traveling faster than the mind can comprehend. 

You can read the full breakdown of just how messy this gets in Randall’s article, but rest assured that the first few hundred thousand peasants, the target of the pole throw, and pretty much everything within a 10-mile radius is going to instantly disappear inside a thermonuclear blast. 

Why the Peasant Railgun Doesn’t Work

Ok, before you start getting over-excited for your next session, there are so, so many reasons why the Peasant Railgun doesn’t actually work. 

First, it relies on taking the laws of physics and applying them to the RAW in D&D 5e, and then (given how much this concept relies on those laws of physics) conveniently ignores other physical laws governing the universe. 

You also need to ignore the fact that, using the 5e RAW, even if the peasants could past a projectile along a two-mile chain in 6 seconds, the peasant at the front would still just make a melee weapon attack, probably with an improvised weapon for 1d4 + 0 (the Commoner’s Strength modifier) damage. 

There are a ton of other reasons why the Peasant Railgun doesn’t work, from damage calculation and the fact that the peasants’ hands would be melted off by touching the pole, to the much more likely fact that the DM just has the power to say “no, that wouldn’t work.” 

If your DM does this, don’t get mad; they’re the one who’s being reasonable. 

What Can We Learn From the Peasant Railgun? 

The Peasant Railgun is obviously not a practical thing anyone can (or should) try in an actual game of D&D. However, I think it still serves as an interesting demonstration of what happens when you try to “break the game.” 

There are plenty of builds, tricks, and random acts of macgyvery that crop up throughout the D&D community that purport to “break” the rules in some way, and they usually rely on the same bad faith logic as the Peasant Railgun. 

Getting a Peasant Railgun to work involves cherry-picking from two different rulesets: the rules of Dungeons & Dragons 5e and the laws of physics. 

You need to take what you want from one (the action economy and round length) and fill in the gaps with stuff you want from the other (kinetic momentum, acceleration, etc.). You not only degrade both sets of rules, but you end up leaving a whole bunch of other stuff on the cutting room floor as well. 

There are plenty of situations where I would make rulings for things that are accounted for by the rules of physics that aren’t explicitly accounted for by the rules of 5e, but you have to account for them using the 5e rules.

This is where stuff like advantage and disadvantage come in handy so often or making a ruling as the DM without actually resorting to the rules at all – like when a player looking for a secret door tells me they take a hammer and tap all the bricks in a dungeon listening for a hollow sound; they don’t have to roll, they just hear a hollow sound. 

While it’s undeniably a fun thought experiment, the Peasant Railgun should never be more than just that.