How to Homebrew D&D Monsters for Mystery Campaigns

A Guide To Making D&D Monsters Perfect for Mystery Driven Campaigns, With Three Examples!

What the Creature Codex is Missing

The creature codex, Monster Manual, Volo's Guide To Monsters, and all the other content made for Dungeons and Dragons are all missing the most important thing: your campaign. Now, obviously, these books have dozens of dragons, boundless beasts, and basically millions of monsters, but they don't have your campaign. They don't have creatures made for your table, for your plot, for your world, for your game.

The written monsters, beasts, constructs and creatures are fantastic and should be used in most every game or session of Dungeons and Dragons, but there comes a time when you need something that just doesn't exist in the books. That's where homebrew monsters come in handy.

Homebrew Monsters for Mysteries

Dungeons and Dragons has a plethora of monsters, but not all of them are perfect for mysteries. While there are lists of standard monsters that work for mystery campaigns, sometimes, making your own can be an excellent way of customizing the mystery for your players.

Additionally, homebrewed monsters can improve your mystery campaign in a few other ways, particularly if your campaign has a custom setting. Homebrew monsters can help give exposition and worldbuilding information through the monster's characteristics, allowing you, as the Dungeon Master, to give your world more life.

Homebrew monsters can also have abilities and features that fit perfectly for the plot that you have designed. You can create a particular ability that allows monsters to advance the plot or to interact with your players in careful ways.

By going over these three example monsters, we will be able to show how homebrew monsters can add a little extra flavor for your mystery campaigns.

The Intrigue Plot

Intrigue plots are political in nature, typically involving multiple parties who all want something, and will stop at nothing to get it. These types of plots include poison, blackmail, spying, murder, arson, theft, lies and all manner of skullduggery, which is what makes it a popular choice for many Dungeon Masters when planning a campaign.

If this is the kind of plot you are interested in, you might also be interested in a homebrewed monster that would make the intrigue even more, well, intriguing!

Enter the Whisper Pikas. These are a race of small, furry rodents about the size of a small rabbit, with large, swiveling ears and bright, beady eyes. Whisper Pikas are bonded creatures, always born in sets of two. These twins develop a telepathic link they use to mimic and relay sounds across great distances. Mercenary scouts, thieves' guilds, and even paranoid nobles have prized them as stealthy spies.

What makes this monster perfect for an intrigue plot is its main two abilities, which are as follows:

• Bonded Pair: When two Whisper Pikas are within 1 mile of each other, they share all information they hear, even if they cannot see one another.

• Telelink: As a bonus action, a Whisper Pika can telepathically transmit any sound or phrase it has heard in the last minute to its bonded partner within 1 mile. That partner then immediately echoes the sound as if it heard it in its location.

As you may already be thinking, the Whisper Pika would serve as an excellent spy posing as a pet, or like a sending spell that could continue to function where the sending spell may have trouble. In this way, devious NPCs and players alike could use these monsters to gain the upper hand on their political enemies, or find out key information about the mystery of the plot in a unique way. They would be perfect for a party with a Druid or two!

The abilities and stats for the Whisper Pikas were created by WorldSmith's monster generator. It only required some ideas and creativity on the front end, and quickly produced a complete stat block with everything from hit points and ability scores to loot and quest lines.

The Whodunnit

A classic whodunnit involves classic, Sherlock Holmes-esque detective work. For our players, it can mean a search for clues, time spent piecing together stories from quirky neighbors and well-meaning relatives, and, best of all, a chance to wear a monocle.

In a setting as fun as this one, the monsters should be varied in design and unique in motivations. A whodunnit campaign should feature monsters from every alignment and every origin, as well as being worked into the story in a variety of ways. Clever Dungeon Masters will need to acknowledge this aspect of the setting, and understand the need for a creative monster built for a whodunnit Dungeons and Dragons campaign.

That means we need a monster like the Cogwork Sleuth! The Cogwork Sleuth is a construct built to help solve mysteries. A mechanical investigator devised by a retired master detective, it walks the streets investigating unsolved mysteries, dedicated to learning the truth in all things. The Cogwork Sleuth can be unnerving in its pursuits, both because of its dedication and because of its appearance, with long, whirring clockwork limbs and body of burnished brass and dark iron.

Again, the abilities are the focus for this monster, especially as a mystery-centered campaign may have little combat. Here are the three main abilities conjured up by WorldSmith:

• Analytical Memory: The Cogwork Sleuth retains perfect recall of anything it sees or hears for up to 30 days, allowing it to reproduce conversations, diagrams, or crime scenes in exact detail.

• Keen Investigator: The Cogwork Sleuth has advantage on Investigation checks. It can take the Search action as a bonus action once per turn.

• Elementary Intuition: Once per short rest, the Cogwork Sleuth can sense lies and detect illusions within 60 feet for the following minute.

For a classic whodunnit campaign, this type of monster can help the players in key moments, giving them a resource to keep the plot moving and the mystery interesting. By using this monster, a savvy Dungeon Master could effectively world-build a steampunk Victorian world. Adding setting details and history to your homebrewed monsters using the WorldSmith world generator is an excellent way to make a world come to life.

A Noir Mystery

Noir mysteries are dark, gritty, and steeped in moral ambiguity. In these campaigns, the rain never seems to stop, the shadows are a little longer, and the villains are often smarter than the heroes. A noir campaign needs a villain that acts as a puppet master, someone who pulls the strings from the darkness while remaining untouchable.

For this setting, you need a monster that embodies corruption and fear, like The Velvet Cardinal. This fiend appears as a sharply dressed humanoid in a tailored black velvet suit, its face obscured by a featureless porcelain mask. Its presence is announced by the faint clatter of ornamental metal cards and a whispering echo that seems to creep from the shadows. It stalks the back alleys and dimly lit clubs of decadent cities, orchestrating crimes as if arranging a grand performance.

The Velvet Cardinal is the perfect antagonist for a noir mystery because it doesn't just fight; it manipulates. Murders vanish into whispers, blackmail letters appear in sealed envelopes, and every front-page scandal bears its unseen signature.

To make this villain truly terrifying, we focus on abilities that allow it to control the narrative:

• Shapechanger: The Velvet Cardinal can use an action to polymorph into a Medium humanoid it has seen. This allows the villain to hide in plain sight, perhaps posing as a trusted ally or a harmless witness until the final reveal.

• Infernal Command: To maintain control over its criminal empire, The Velvet Cardinal can issue a short, compelling command to one creature it can see within 60 feet, forcing them to obey on a failed save. This explains why witnesses stay silent or why good people commit crimes—they literally had no choice.

• Shadow Step: If the players finally corner this mastermind, it can move up to 20 feet without provoking opportunity attacks, disappearing into shadows and reappearing in another spot. This makes capturing the Cardinal a puzzle in itself. It could also make traversing dungeons simple for the Velvet Cardinal and difficult for your party, depending on their abilities.

If you are planning to pit your party against a CR 12 mastermind like this, you should click on the WorldSmith encounter generator to ensure the fight is balanced. You want the battle to be difficult, but not an accidental TPK.

Is a Monster Generator Necessary?

In order to create these monsters, we've used WorldSmith's Monster Generator, which does an excellent job creating creatures, dragons, beasts, and other homebrew monsters for our games. It gives descriptions, lore, stats and other data for the monsters it generates. WorldSmith is also able to do so quickly, helping reduce prep time and balance encounters. WorldSmith was built with the Dungeons and Dragons 5e system in mind, but it can be system agnostic with some tweaking, depending on the system you are using for your game.

However, it isn't necessary to use a monster generator! It is completely possible to go create monsters on your own, picking out features from different beasts or monsters and creating stat blocks around them. This is especially useful if you have particular races, designs, or abilities in mind, or if you are working with a specific system that is more tricky to work with. Generators like WorldSmith can help bring these ideas to life, but if you want to select specific features from specific sources or books, it is completely possible to do so on pen and paper.

There are plenty of options when creating your own monsters, which is most of the fun of it! You can create monsters with your imagination, based on whatever features, sources, ideas, systems, games, or content you have in mind. Many homebrew monsters can be used in Dungeons and Dragons come from fiction books or comics you've read, movies you've seen, or any other sort of media that you love.

Solving the Case with Custom Monsters

Creating mysteries in D&D requires a delicate balance of pacing, clues, and tension. A well-designed homebrew monster acts as both a plot device and a mechanical challenge, bridging the gap between narrative and gameplay. Whether you are running a high-stakes political drama with a race of beasts like the Whisper Pikas or a gritty noir detective story featuring The Velvet Cardinal, the right monster can elevate the entire experience.

However, balancing these unique abilities against a party of inquisitive players can be difficult. Tools like WorldSmith take the heavy lifting out of this process. You can input a vague concept—like a "clockwork detective"—and get a fully realized stat block like the Cogwork Sleuth in seconds, complete with the math for Challenge Ratings and Save DCs already handled.

If you need rewards for solving these mysteries, the WorldSmith treasure generator is an excellent resource for creating plot-relevant loot, such as the Demon Ledger or Obsidian Sealed Card dropped by The Velvet Cardinal. So, don't settle for generic thugs in your next mystery. With a little creativity and the right tools, you can craft adversaries that keep your players guessing until the very end.