Monster Making 101: The Basics

A Brief Foreword

I realized that I really wanted to ramble for a bit about building interesting monsters from the ground up, but then that I also needed to set a baseline of what it means for a monster to be interesting and some of the goals I hope to achieve with each of the later posts in this series. As a demonstration, I've also included a statblock at the end of this post, a breakdown of the monster in question, and an encounter using said monster.

What Makes Monsters Interesting?

To start answering this question, I'll start with what makes them boring; tactical inflexibility. Now likely, you think of the monsters that because they've got limited options (both in the statblock and in the encounter design) are limited to doing the same thing, over and over again, with no variability when I say that. That can be boring if used poorly, but what I'm really talking about is monster design that results in tactical inflexibility for the players. Essentially, monsters that let the party skate by with just their bog standard tactics on autopilot; Drop a control effect on the biggest group of foes or to otherwise subdivide the encounter, focus fire on the biggest threat that's not controlled, then work your way down the proverbial food chain.

I'm not saying that letting your players have those encounters where they get to chill out and fall back to the old-reliable tactics are a cardinal sin, in fact, those encounters are an important part of pacing out adventuring so that the party gets to have fun and do what they're good at. It's a classic case of "Shoot your monks." Those encounters are great, but like any good thing, too much of it just gets stale. What I'm talking about with interesting monsters is the ones that shake up that formula, push the party just a bit outside their comfort zone, and let them engage in the off-the-wall problem solving that really makes TTRPGs so special.

Core Design Philosophies

With all of that said, here are the core principles that I keep in mind when building my latest horrific abomination to throw at my party. These aren't hard and fast rules, I break them all the time, but they're general guidelines that help make every encounter memorable.

1. Keep the monsters interesting. Like I said above, we're not putting in all of this effort to design a monster just for it to be a big sack of HP that stands perfectly still and goes stab stab stab while the party does the same thing they literally always do.
2. Make monsters memorable. Give the monsters something that sets them apart from other things your party encounters. It could just be a distinctive set of equipment, a unique description and behavior, an unnatural durability against a particular type of attack, or an ability that does something your party has never seen before.
3. Restrict player agency, don't remove it. Give your monsters abilities like Slow, Tasha's Mind Whip, or Plant Growth that interfere with player actions rather than things like Hypnotic Pattern and Hold Person that prevent player actions. It usually takes at least 5 minutes between turns, so having a turn fully skipped or otherwise negated can really suck.
4. Give monsters flaws. Every monster should have a weakness, even if it's not an obvious one. Don't be afraid to make a monster that's resistant/immune to most forms of damage but can be easily damaged/hampered by something in the environment it's fought in. That makes for an interesting puzzle encounter for your party to solve.
   
5. Keep monsters simple (except bosses). If you need anything more than a paragraph or two to describe a monster's combat tactics and it's not meant to serve as a standalone boss, it's probably got too much going on in its statblock.
6. Come up with a modus operandi. Once you have a statblock, try and put together as simple of a description of what the monster does as possible, so that you can easily refer back to it later.
7. Remember that fighting the monster isn't the only solution. Monsters ultimately are hazards to be overcome, not just bodies to be looted and then put in the ground. Give them personalities, wants, and desires. Maybe the big, scary troll lurking in Room 5 of the dungeon really hates the goblins in Room 3, and will happily leave you alone if you get the annoying little shits to leave it be.

 

Example Monster: Brigand Bruiser

 

So, let's start with the basics. This is a big melee bruiser, designed to get up close and personal with your players and ruin their day. Given it being a CR 4 enemy, it works well as a beefy henchman for a mid-level villain, or as the boss of a bunch of lesser thugs that are the antagonists of a lower level party.

1. What makes it interesting? This is a basic melee bruiser, but it can inflict a variety of conditions, can reposition enemies, can make interesting tactical choices through positioning, and can perform interesting combos both on its own and with allies.
2. What makes it memorable? This brigand is using a weird combination of weapons; a flail and a greatknife that it dual wields. Given its brute trait and high strength, it's probably a hulking behemoth of an outlaw, and given the power of this brigand compared to common bandits, they've been at it a while, so they're likely in a position of power, covered in distinctive scars, and a wanted criminal.
3. The brigand's primary control effects are forced movement (Flail attack and Shoves), the Poisoned condition (Disadvantage on attacks and ability checks), and reduced speed (Grappling and Shoving prone). All of these serve to hamper players, without outright preventing them from doing anything.
4. The flaws are pretty straightforward here, as I stated, this is a big (dumb) melee bruiser. Its ranged attacks are seriously lacking and its saving throws are unimpressive.
5. Honestly this is about as complicated as a non-boss, non-spellcaster enemy should get. One or two passives, one or two rider effects on its attacks / special abilities, and a bonus action or reaction.
6. What's the modus operandi? The brigand picks a weak-looking target that it can reach with its movement speed, aims to poison it with its greatknife, then grapple it to prevent it from fleeing as its allies close in. On its next turn, it shoves the target prone, then attacks with its flail if the target is poisoned, or greatknife if the target isn't poisoned until either the foe is defeated or a bigger threat makes itself clear. If it can't reach anyone with just its movement, it bonus action Dashes, then either action Dashes, or uses its crossbow before drawing melee weapons and reverting to normal tactics. If it has to flee, it either uses its Flail to batter foes away (if it has allies in range that also want to flee), or uses the Disengage action (if it's on its own or seriously outnumbered in melee) and then Dashes as a bonus action.
   
7. What does the brigand want that the party could exploit to avoid combat? The brigand is a straightforward one. Presumably they're an ex-soldier who turned to banditry in times of hardship to get by, so likely they're looking to acquire food, coin, and whatever creature comforts can be had wherever they're hiding from the law. They might have a grudge against other criminals in the area, or a particular officer of the law that they're on the run from. The party could reasonably parley and offer any of these things at most points before or during combat. The brigand isn't out here to die, they're here to make a living, and a heavily armed mercenary band (Read as: The Party) is a big threat to that way of living that is to be threatened and bargained with before a fight or escape attempt plays out.

The Sold Swords

Led by the infamous Theramar the Red, the Sold Swords are but one of many groups of bandits that sprung up after the war of the last few decades ended in defeat. With naught but burnt homes and razed fields to return home to, these deserters and broken men united under their old captains and took up arms once more. Some say they did so to carry on the fight even after the old king's army was crushed, while the pragmatic say they did it just to survive.

Theramar is a hulking orc, nicknamed the Red for the massive burn scar that's frozen the left side of his face into a perpetual snarl. He claims the scar was gained in the last battle of the war when he just barely survived a mage's fire while directing his men to safety, and the oldest members of his troop of bandits attest to the tale. Theramar is a brutish, short-tempered man, but his expertise, intimidating demeanor, and genuine loyalty to his men keep the Sold Swords operating as a united front. As an expert survivalist and disciplined soldier, Theramar makes use of the hostile wilderness and guerilla tactics to rob caravans and evade pursuers alongside his band of two dozen bandits. They maintain a base camp hidden deep within the forests, but only an expert tracker would be able to tail the group back to their lair.

Example Encounter: Caravan Guards

The party have been hired as a group of caravan guards to escort a local fur-trader through the King's Wood so that the caravan can safely make it to market. The road follows a winding path through the forest before reaching the fortress at King's Crossing on the Lannsford river, and the Sold Swords are known to be active in the area. The party are likely aware of the rumors of the Sold Swords prior raids and Theramar's reputation, and thus they know that handing over a portion of the furs would be enough to guarantee safe passage. However, they've been offered twice the original rate if they manage to fend off the brigands without needing to give up the cargo.

The journey goes smoothly until the party reaches a tight bend in the road about a day's travel from King's Crossing. The bend is tight enough that visibility along the road is restricted to no more than a hundred feet and the dense undergrowth and tree cover alongside the bend provide ample cover for an ambush. Naturally, the Sold Swords make their appearance here. Theramar initiates the raid, calmly stepping out in front of the caravan to block it's path. In the underbrush lurk 2d6 + 4 bandits with their crossbows trained on the caravan with readied attacks if things go south. Theramar leads with a mix of Intimidation and Deception, using a blend of threats and bluffs to convince the party that the wisest course of action is to hand over half of their cargo, as their odds of taking on his (exaggerated) number of allies. The bandits laying in wait will deliberately rustle foliage all around the party (ideally from a distance with ropes) to give the impression of a much larger offensive force.

If the party acquiesces, half of the bandits emerge from the foliage to collect the goods with their scimitars drawn, while the remaining half stay in position with their crossbows in case the party is using this as a lure. If it is an attempt by the party to lure the bandits out, they proceed with combat as below.

If hostilities break out, half of the bandits in the foliage unload on any party members that are visible (with a preference for anyone unarmored or only lightly armored, while the remaining half Dash into melee range with scimitars drawn. Theramar closes to melee with the nearest foe, and attempts to knock them unconscious to use for a hostage negotiation to get the cargo. Any individual bandit retreats into the foliage when reduced to 5 HP or lower, Disengaging and then loosing crossbow shots until out of short range, then Dashing. Theramar retreats when reduced to 25 HP or fewer or when at least half of his men have fled. Regardless, he retreats just behind his men to cover their retreat until everyone is in the foliage, whereupon the bandits scatter in every direction and eventually loop back to their hideout. If Theramar is defeated, the bandits scatter immediately. Every route they flee by is likely riddled with pit traps, snares, and other nasty improvised traps to hamper would-be pursuers, and likely has several designated points where the bandit will double back, cross small streams, or loop over their own tracks to further hamper pursuit.

If the party hands over the requested goods, Theramar lets them go with half of their wares, and they are unmolested for the rest of their journey, though their patron merchant is likely rather upset. If a fight breaks out, Theremar aims to incapacitate and subdue rather than to kill, leaving characters unconscious to bleed out rather than finishing them off. Theramar's Intelligence and Wisdom combined with his combat experience are good enough that he can direct his men's attacks to where they'll be the most effective, to roughly gauge the capabilities of the party, and to determine when would be a good time to either press the assault or cut losses and retreat. His goal is to either retrieve the cargo, or to escape with the majority of his men alive. If the party is defeated, anyone who succeeds on their death saving throws will awaken a few hours later, the caravan fully looted, and themselves stripped of any supplies, valuables, weapons, and armor that could be useful to the bandits.

Encounter Post-Mortem

Essentially, this is a breakdown of how to design and run a statblock as an encounter with open-ended solutions. The core principles on display here can be used with pretty much any statblock, even a pre-made one (though it might need some small tweaks to really work well). The party can either take a straight up fight, hand over the goods, or do something in-between. Maybe they hand over the goods, then trail and ambush the loot-laden bandits as they celebrate at camp that night. Maybe the party loses the fight, and thus swear vengeance on the Sold Swords. Similarly, maybe Theramar holds a grudge against the party for fending off his raid, and the party will find themselves harried and ambushed on future travels throughout the area. Regardless, the goal here was to make something more interesting than a simple bag of hit points that does damage, and it's been accomplished. This is the kind of encounter that is a serious challenge for a party of levels 1-4 (and the party's relative strength will likely dramatically influence their approach) and can even be thrown at higher level parties by just tuning the numbers slightly, maybe there's more bandits, or some of the ones that enter into melee are replaced with bandit captains, etc.