I think a lot of Players in D&D like to underestimate Devils. Part of it simply comes from being the main characters in the game – the Players generally like to assume that they’re in charge of how the story is going to go – and partly because they think that something so comically evil as a red-skinned, musclebound, horned man with a barbed tail can’t be that serious.

Well, unfortunately for them the Pit Fiend not only is that serious, it is fantastically deadly.

It’s stronger than your Barbarian, smarter than your Wizard, and more charming than your Bard. It outclasses your Party members in nearly every stat, and has the full weight of the Hells behind it.

And if your Players aren’t ready for just how dangerous the Pit Fiend is, then they’re walking blindly to their own destruction.

Clocking in at a solid CR 20, you want your Pit Fiend to be one of the heaviest hitters of your campaign, very probably orchestrating all of the chaos your Players are hacking their way through. These creatures are just below the Archdevils in terms of infernal power, so they have access to all of the resources and firepower they need in order to execute their plans.

This means that you need to come up with a plan worthy of such an adversary well before you ever worry about what happens when your Party starts fighting them.

Generally, the creatures of the Hells are interested in the use of power through corruption. On a practical level, there’s the never-ending battle with the Abyss that they have to keep fighting, but in order to gain the resources and souls to fight that battle, they need to corrupt otherwise decent people on the moral planes.

A petty demon like an imp or an Incubus might go for one or two people at a time, developing artisanal, hand-crafted misery that turns a single soul into a screaming, twisted shadow of its former self. And while that’s certainly fun in its own way, a Pit Fiend is going to need more than that in order to further its plans.

A Pit Fiend should target nations.

There’s a kingdom in your world that used to be a wonderful place. It had festivals and culture, and brought people from near and far to join its celebrations and become part of its grand tapestry of life and art and scholarship. Of course, no nation is perfect, but all in all, this one was pretty good.

In the last few years, though, this kingdom has been in decline. Less open, less trusting. Instead of producing great art, it has consumed and regurgitated it into pale imitations that it called beautiful. People don’t trust their neighbors and have no faith in their institutions, and the unrest means that the rulers have to wield a stronger and stronger hand in order to maintain their power.

Some people may have left this kingdom, heading for places that are less hateful and poisonous, and lament the way their homeland has changed. “How could this happen?” they ask?

The truth is, this kingdom has fallen under the eye of a particularly powerful Pit Fiend. The Fiend has decided that the souls here were fruitful and useful and ready for the harvest, and so began the process of corruption. As far as most people know, this is simply the natural decline of a nation – happens all the time, if you read your history. But those attuned to the world of Fiends know that this has become a center for devilish interference.

This is not the inexorable flow of history. This is intentional. The Pit Fiend doesn’t want to destroy the kingdom – any blundering Tarrasque can manage that. The Pit fiend is a planner, a thinker, a devious and cunning administrator of infernal systems and it wants this kingdom as a fully-functioning soul factory.

And that’s how your Party gets involved, as perhaps a person sends them their conspiratorial notes, claiming “THEY THINK ME MAD!” before vanishing into the sullen, angry crowd. Or priests of the Cleric’s god begin to suffer from crises of faith, their belief shaken by visions of how small and futile they are. Or fiendish incursions increase, trapping people in complex webs of contracts they had no chance to understand before accepting gifts they did not know they wanted.

You can use all the Devils in the Monster Manual for this adventure. Spined Devils are the information-gatherers, pulling rumors and gossip together into plausible-sounding news that sets neighbor against neighbor. The Ice Devils keep the plan moving with cold, logical precision, removing empathy from the equation with clinical accuracy. Incubi target specific key individuals whose corruption can influence others. And the Erinyes, ever cruel and precise, manage the whole thing from the largest to the smallest scale.

Your campaign can be entirely about unraveling this grand, fiendish conspiracy, until they are powerful enough to finally face the Pit Fiend on their own, a fight that should test their limits and cleverness. Simple getting close to the Fiend requires a Wisdom saving throw against being Frightened, which will put them at disadvantage right away. While they are frozen, unable to come closer, the Pit Fiend hurls Fireball after Fireball at them, paralyzing their bodies or simply erecting a Wall of Fire to keep them away as its minions take them down.

And oh yes – your Pit Fiend will have Minions. These are some of the most powerful Fiends in the Hells, and have access to countless lower beings to put between them and any meddling adventurers who think they’re strong enough to face them. As far as the Pit Fiend is concerned, this will be an easy victory.

Should your Party get close enough, however, the Fiend has four attacks per round at its disposal, dealing physical and elemental damage each time. And if a character is unlucky enough to be in range of the Bite attack, they run the risk of being Poisoned, taking damage each round, an being unable to regain health.

If your Players think they can just charge in and fight, they’re probably going to die. And justifiably so. But it’s possible for you to lace this information into the story, through rumors, records, and lore, that can allow them to approach this final battle intelligently.

And in the end, when they finally have the Fiend at their mercy, it might reveal to them just how easy it was. How people are so eager to turn on each other, to be suspicious and judgmental and cruel, and all it really took… was a push. A few key people had a few bad days, and the rest was just a matter of making sure the giant thundering boulder rolled downhill in the right direction.

That may be the last sting that takes the surety out of your Players’ victory, if that is something you want to do.

Anyone who watches our world knows that there are no eternal beings meddling in its affairs. All the worst things we do are things we do to each other, with no fiendish assistance necessary. In the real world, the “boulder rolling downhill” is just… gravity.

But we don’t play D&D to reflect the real world. We play because we want to believe that Evil has a name, a stat block, and a weakness. We want to believe that the rot in our institutions isn’t an inevitable flaw of human nature, but a tactical error by a monster that can be punched in the face.

A group of friends with a free Saturday can’t fix a failing real-world nation. But they can take down a Pit Fiend. And in that moment, as the red-skinned general vanishes into ash and the sun breaks over a liberated capital, we get to pretend that the world is a place where goodness is the natural state, and every devil has its day.