Merfolk 5e
Guide by Sam West, @CrierKobold
See also merrow, sahugin, giant sea horses, and reef sharks
Below the waves can have as rich biomes and diversity flourish as above; where humans and their kin call land cities home, the aquatic merfolk hold domain over the sea. They are the undersea version of commoners and usually are the default first neutral encounter players may have when venturing below.
Merfolk are a blank aquatic canvas which DMs can do all kinds of neat things with. At their baseline, they’re an easy encounter to help teach players about the perils and complexities of underwater combat. Beyond that, they fill the same role as any intelligent species that forms societies and come with all the complexity thinking and feeling people come with.
Goblins and kobolds tend to default towards being “evil” monsters. What sets Merfolk aside from their ilk is their base neutral state. You’d want to run Merfolk over something like a Sahugain when you were looking for moral ambiguity, or when introducing a new grouping of people that have thieves and nobles just like humans.
Running Merfolk
Non-tactical merfolk run as part of a monster meat grinder are weak. They compare poorly to even the humble Goblin and Skeleton as far as damage and options go if you strictly look at their stat block- if they just sprint at the party and attack till death, they’re going to get slaughtered.
Merfolk encounter challenge comes from their environment and tactics. What’s outside the stat block matters a lot more when their only notable traits are underwater breathing, a 40 ft. swim speed, and a spear.
Player Levels
1st level players can take down a small group of Merfolk without too much issue should they be in a “fight to the death” scenario with the party’s size or fewer enemies. With just their spears, they will fail to drop any one character without a crit, and even on a crit, most classes can survive the blow if they have a positive constitution modifier. As long as the players can get to and hit the fish people, they shouldn’t struggle with this encounter thanks to their class abilities.
The environment and party’s ranged options contribute to the chances of success in such a low-tier fight, as given the space, merfolk can skirmish players to death by out-speeding them and pelting them with endless barrages of spears should the environment support it and the players don’t ready actions when needed.
Juicing up Merfolk to combat higher-level players is super easy, and it's all about leveraging their speed and stacking new tools onto their bare-bones stats.
Defining Gameplay to Work With
Merfolk are the perfect “intro to underwater combat” monster. Beyond being the aquatic humans of many worlds, they are what you introduce players with to get them used to the underwater combat rules without running the risk of getting thrashed by enemies with a wider variety of tools available to them.
Beyond their amphibious trait, their 40 ft. swim speed helps them outpace most low-tier parties, especially those lacking swim speeds of their own. Their Spears are thrown; each has an option to attack from range when engaging or disengaging. Having them carry a set amount of these will massively add to their tactical options, as they’re going to want to keep a lot of space between larger martial characters with threatening melee attacks while picking off squishier targets from a safe distance.
There are three important sets of rules to play around with when introducing merfolk: the Suffocating, Underwater Combat, and Swimming rules. I’d read up on these before planning merfolk encounters, as they greatly inform how merfolk can take advantage of them over land-based creatures.
This matters most in terms of how ranged weapons work. If you aren’t using a crossbow or thrown weapon, your weapon automatically misses. Given their quick speed and ranged spear attack, if you get caught with your only ranged option being a longbow and Fire Bolt, your party is going to have a bad time.
Mentality and Tactics
With only spears to work with, Merfolk want to play in groups and follow 5e’s basic tactics. They want to focus one creature at a time and to drop the party’s actions as fast as possible. Given their intelligence, they probably want to prioritize the lowest hit point highest threat party member, and can usually recognize that taking out threats that can match their speed or range should be the priority.
They can use the three-dimensional space to easily navigate around clunkier and slower characters, poking at them as they go.
Spears
A major element of their character sheet is their “spear” attack, which has a thrown ranged mode. How many spears you arm them with, then, determines a major element of how threatening they can be.
Single Spear: If they’re all armed with a single spear, when they decide to throw it adds some high-risk decisions to consider, ideally only aiming for targets they think they can meaningfully drop, as otherwise disarming themselves is too high a cost.
Multiple Spears: Given they can carry up to one hundred and fifty pounds worth of items, and spears only weigh 3 pounds each, I’d expect them to have holsters with multiple spears available. It's the first easy step to add complexity to the fights and juice up their lethality.
With five or more, I’d expect them to stay only within the long 60 ft. range, taking pot shots with disadvantage on lower AC targets until they’re weak enough to clean up with their remaining few spears from a closer distance.
They can also dip into short range, chuck a spear, and dip back out of a player’s typical engagement range, as a character with no swim speed and a base land speed of 30 can’t even Dash within range of this poke and run strategy.
Any large objects and cover add a huge amount of dynamics and decision-making to the encounter that otherwise looks miserable on paper with the party surrounded and getting poked to death. Using wrecked ships with multiple levels and layers players and merfolk alike can use for cover can quickly add up to a suspenseful, terror-inducing timed survival mission with the merfolk more than happy to wait out the player’s breath.
Combating the Monster
The easiest way to combat merfolk is the tried and true strategy of whacking them with a hammer. The trickier part is getting and staying in range.
They can always outlast a group underwater without underwater breathing of some nature. They know land-dwellers need air, and can use that to set up ambushes with enough cover. Patience is key to their chances of winning; this forces you, the players, to make the first move.
Methods of Engagement
Some environments are losing environments against merfolk. When run tactically and coupled with complex environments you’re going blind into, you’re asking to get massacred or drowned, especially if you don’t have a reliable way to damage them from 60 feet out or get and stay on top of them. You need to be able to handle them from a distance or have a plan to keep them still and hit them.
Being underwater automatically puts most lower-level groups at a disadvantage. Casting Water Breathing solves 90% of your problems at once- you now have enough speed to keep up, can use most of your weapons normally, and can’t be out-lasted by them as easily.
Merfolk also need light to see, where many player characters may not. You can use darkness to plan and set up attacks, and depriving them of light in deeper environments can keep you and your party protected.
Elements to Target
Locking down groups together with spells like Rime’s Binding Ice and Web can remove all of their advantages at once, allowing you and your other melee allies to get on top of them and make quick work of their small hit point pools.
If they stay spread out, which they definitely should, you’re almost always going to want to deal as much damage as you can as fast as you can. They’re not working with a high armor class, nor lots of hit points; the sooner you can get 11 damage in, the sooner you win the day.
If you can’t get a swim speed, you’ll want a spear or shortsword most of the time for your melee weapon. For ranged options, daggers are going to likely be your on-hand option for rogues and rangers, and you are likely going to need to throw it. Having multiples helps a ton. Ideally, come with a crossbow so you can fight back as they chuck spears at you from 40 feet away.
One last tactic to keep in mind is readying actions. If they’re moving in and out of your weapons’ thrown ranges, instead of hopelessly swimming at it at a snail’s pace, readying your dagger to throw when it moves in to strike gives you a fighting chance of taking it down over a round or two of that attack pattern.
Classes That Shine Against It
The second a party has access to Water Breathing, the bulk of the concern of these fights is lost. It's a ritual spell most 5th-level casters can access; those all help a ton against these underwater fights.
After that, classes that can trap them and deny their 40 ft. speed outrunning the party are incredibly helpful. The reality of fighting in 3-D space makes this harder than you’d initially think, with spells like Entangle and Spike Growth not functioning when the ground is dozens or hundreds of feat away. Web only lasts a round when not anchored to a surface, but at least can restrain them long enough to prevent easy escape.
Rogues have a bonus action dash to navigate around the waters more easily than most. They also tend to favor weapons that work fine underwater as well; with a Sneak Attack empowered crossbow shot, they can drop a merfolk in a single bolt with ease, punishing them for trying to wait you out as you benefit from hiding around and taking shots from stealth.
Merfolk in Your World
As mentioned above, Merfolk are the humans of the sea. It's their job. They can have as rich a society and culture as you make with diverse groups offering wide variation in presentation and appeal.
As the Main Antagonist
Like any humanoid, a Merfolk can be a compelling villain with some class levels or other features tacked on. Slapping a 40 ft. swim speed, 10 ft. land speed and Amphibious trait to any humanoid stat block can functionally make it a merfolk, opening up all kinds of higher CR possibilities.
What sets them apart is their aquatic nature; their lackeys and motivations all are going to reflect their underwater world first and foremost. They could go full aqua-man villain and seek to drown all land-dwellers or play a more complex role in wanting to end island-fairing societies that are encroaching on territory they’ve deemed rightfully theirs. There is a lot of nuisance that comes with these kinds of villains, as well as the possibility for moral complexity.
What is a bit easier to digest beyond villainous motivations are their underlings, simply because there aren’t as many aquatic beings as there are non-aquatic. A merfolk villain is the perfect place to introduce lackeys primed for underwater combat.
The following underlings table can play well with lower-tiered merfolk villains, like a pirate leader or violent sovereign.
Underling Table
| d8 | Underlings |
|---|---|
| 1 | A crab, quipper, or octopus familiar |
| 2 | A pod (1d4+1) of trained war dolphins |
| 3 | Giant sea horse mounts for them and their fellow merfolk warriors |
| 4 | Trained hunting reef sharks, similar to hunting dogs |
| 5 | A captured Plesiosaurus kept in a small cave with an air pocket for it |
| 6 | A lone sea hag the merfolk has made a bargain with |
| 7 | A band of Merrow they work with in secret |
| 8 | Animated pirate skeletons, forming a macabre crew for the shipwreck |
As a Supplementary Monster
Merfolk, unaltered, are easy fodder to stick to a larger leader. Powerful merrow or sahuagin leaders can conscript these weaker statted creatures to work for them, even if it may end up being against their best interest. They’re like humans- free will opens them up to be easy cultists of deep monsters just as well as it sets them up to fight for good.
The Overlord table has sample leaders that merfolk could follow and supplement well in combat.
Overlord Table
| d8 | Overlord and Relationship to the Merfolk | |
|---|---|---|
| 1 | Cultists to an ancient slumbering Kraken | |
| 2 | Conscripts of a Storm Giants army who promises them glory and territory for service | |
| 3 | Hired muscle working with a Blue Dragon to rid a region of sailors | |
| 4 | Merchants and spies for a nosey Marid looking to spread influence on the material | |
| 5 | Explorers who lost their minds to a sunken Mind Flayer, now servants to it | |
| 6 | Subjugated slaves to a twisted Merrow or Sahugin ruler | |
| 7 | Unknowing actors enacting archaic rituals for an Aboleth in their sleep | |
| 8 | Servants worshipping a Death Tyrant or Lich that decimated their society |
Environments
Merfolk want to be entirely submerged. They aren’t going to make threatening or interesting villains on dry land where they crawl around with the same speed as some fungus.
You can take most above sea level environments and create a mirror of that underwater with some magic and real-world inspiration. A magnificent forest of hundred and thousand-year-old trees can convert into a kelp forest with rich, green stalks blotting out the sun in their masses. Ports may look like buoyant objects being tied to the sea floor the merchants use to move wares between realms. Cities, towns, and urban environments translate nearly one-to-one, but offer verticality that can enable round, dense environments that can be explored in all three dimensions with ease.
The following environment table highlights a few areas merfolk can shine as monsters in. These environments all play around with how much space the players and merfolk have to navigate.
Environment Table
| d8 | Environment |
|---|---|
| 1 | A shipwreck midway through being searched through by merfolk scavengers |
| 2 | The bones of a land behemoth dragged below turned temple to the monster that felled it |
| 3 | A thriving merfolk marketplace with chains holding the floating stalls stacked in place |
| 4 | A network of tight, interconnecting caves that dip in and out of water |
| 5 | A lake houses a colony of merfolk who use the streams and rivers around it for their mercantile lifestyle |
| 6 | A merchant ship under siege from below |
| 7 | A coral reef flush with life and some coral structures dwarfing ancient trees |
| 8 | A narrow chasm dotted with pockets of earth erupting toxins into the environment |
Quest Hooks
Merfolk offer great mysterious plot hooks- often, an assumption is made about how a creature can get into somewhere by nature of its legs. Quick aquatic creatures, like merfok, performing villainous acts at sea or on coasts can be challenging to track and naturally make for fantastic thieves and pirates.
If you’re looking for ways to introduce merfolk to your game, the following table of quest hooks can quickly get your players invested in confronting these seafaring foes.
Quest Hook Table
| d8 | Hook |
|---|---|
| 1 | A ship never arrived at port; rumors have it is wrecked near the coast and full of loot |
| 2 | A merchant craves more of a rare pigment produced below the waves, and needs a group to venture to the merfolk to establish a consistent trade between them |
| 3 | Merfolk bandits have been pilfering goods from a lakeside town at night, and have a hefty reward placed on their leader’s head |
| 4 | Diplomacy is breaking down between nations overseas, but diplomats can’t get to them safely without passing through forbidden merfolk territory |
| 5 | Fishermen have been disappearing from popular fishing spots as a merfolk looks to widen their territorial claims inland |
| 6 | A storm giant has presented an ultimatum to a coastal town; the town is in need of allies, and shares a common enemy with the merfolk tormented by the giant’s reign |
| 7 | An envoy from a merfolk colony is in search of air-breathers to aid in their plight against a merrow warlord |
| 8 | Territorial disputes have risen to peak tension as an island people wage war against the merfolk that keep them land locked and out of their waters |
Associated Loot
The easiest way to give players the tools to explore underwater is through loot merfolk could have on them. Looters and pirates can take the precious aquatic magical gear they pilfer from their victims, and otherwise have similar magic items land dwellers find useful in exploration and combat.
The following table has some early-tier items to incorporate with merfolk to offer the party better tools in aquatic adventuring.
Item Table
| d8 | Item |
|---|---|
| 1 | A few Caps of Water Breathing |
| 2 | A Cloak of the Manta Ray |
| 3 | An ornate Decanter of Endless Water |
| 4 | A Driftglobe, to illuminate the depths |
| 5 | Gloves of Swimming and Climbing |
| 6 | Goggles of Night |
| 7 | Mariner’s Armor, attached to a corpse with a spear pinning it to the sea floor |
| 8 | A Ring of Swimming |
Making the Most of Merfolk
With these tactics in mind, you should have an easy time presenting merfolk that can pose reasonable threats to early tier groups as well as have ample tools to juice up merfolk encounters and incorporate them into your world. Good luck down there where it's wetter!
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