Merfolk are mythological creatures that have the upper bodies of humans and the lower bodies of a marine animal. They are prominently featured in [[Magic: The Gathering|MTG]], [[RPG|RPGs]], and even [[Warhammer 40,000|40k]] had a [[saharduin|minor aquatic race at one point]]. Merfolk are also major races in many videogames such as the Zora from [[Legend of Zelda RPG|Zelda]], the Naga from Warcraft, and the Slithereen from Dota2. [[/tg/]] has had a spattering of threads dedicated to merfolk over the years where it has [http://suptg.thisisnotatrueending.com/archive/27484548/ discussed how an underwater civilization would develop], and many people have wished to use merfolk characters or merfolk cities in their campaign. Unfortunately most settings have rules that are not conducive to using merfolk as player characters, fluff that does not include merfolk as a major power, and a lack of effort to describe a thriving merfolk civilization. This page serves as a hub to organize and advertise all the merfolk content that the community has created to solve this problem. It is an attempt to create rules and fluff for PC races of merfolk that can be used in any campaign. If you like merfolk or other underwater themes, feel free to create anything you want and make a link for it on this page.
'''Merfolk''' are mythological creatures that have the upper bodies of humans and the lower bodies of a marine animal, almost always a fish. They originated in medieval folklore as '''mermaids''', creatures that would seduce blueballed sailors to drown them (mermen were invented sort of as an afterthought to explain procreation). They are prominently featured in [[Magic: The Gathering|MTG]], [[RPG|RPGs]], and even [[Warhammer 40,000|40k]] had a [[saharduin|minor aquatic race at one point]]. Creatures similar to merfolk can also be found in many videogames, such as the Zora from [[The Legend of Zelda]], the Naga from [[Warcraft]], and the Slithereen from Dota2.
== Merfolk Races ==
[[Dungeons & Dragons]] and [[Pathfinder]] generally have given merfolk only lackluster attention, as their unique body configuration makes them to all practical purposes useless on your typical land-based campaign, but, if you add them into a "surfacers gone underwater" campaign (itself a rarity), they tend to be overpowered, as they are faster and don't need to worry about breathing underwater. D&D usually tries to push the [[Triton]] over the merfolk as a consequence, as Tritons at least can try to partake in both underwater and traditional campaigns.
The Merfolk are the mysterious and secretive people who have populated the world’s waters, and they are as widespread as humans are on land. Communities exist in mountain lakes, coastal reefs, kelp forests, rivers, and even inside polar ice shelves. They are an ancient species with many subraces. The vast expanse and depth of the world's oceans conspire to keep many of these races undiscovered.
Still, despite their issues, [[/tg/]] has had a spattering of threads dedicated to merfolk over the years where it has [http://suptg.thisisnotatrueending.com/archive/27484548/ discussed how an underwater civilization would develop], and many people have wished to use merfolk characters or merfolk cities in their campaign. Unfortunately, most settings have rules that are not conducive to using merfolk as player characters, fluff that does not include merfolk as a major power, and a lack of effort to describe a thriving merfolk civilization.
! Image
! Race
! Description
|-
| [[File:Coastal Merfolk.jpg|thumb|75px]]
| '''[[Coastal Merfolk]]'''
| The Coastal Merfolk are an aquatic race that has populated many of the world’s oceans. Communities are most common along on the continental shelf of temperate regions. They are an ancient species and are therefore even more physically diverse than humans. They are a cosmopolitan and mercantile society and most Coastal Merfolk are competent tradesmen.
|-
| [[File:Coralmerfolk2.jpg|thumb|75px]]
| '''[[Coral Merfolk]]'''
| Coral Merfolk are a tropical race of merfolk that are known for their dramatic and beautiful multicolored skin patterns. They usually have small to medium size communities around atolls, islands, and reefs. Coral Merfolk blood is naturally magical which allows many to become talented spontaneous spell casters.
|-
| [[File:AbyssalMer.png|thumb|75px]]
| '''[[Abyssal Merfolk]]'''
| Abyssal Merfolk are an evil aquatic race that dwell in the dark depths of the oceans. They are known for their cruel militaristic society that frequently launches raids into the surface world to capture slaves and plunder.
|-
| [[File:Arctic merfolk.jpg|thumb|75px]]
| '''[[Arctic Merfolk]]'''
| The arctic merfolk are large and powerful aquatic race that live in the cold northern waters of the world. They are a proud and noble race who have a strong sense of right and wrong. Live under ice sheets and in glacial lakes and rivers. large size? dolphin/whale?
|-
| [[File:Selkie pose by stressedjenny-d58j8fh.jpg|thumb|75px]]
PC stats for merfolk in [[Advanced Dungeons & Dragons]] 2nd edition can be found in the article "heroes of the Sea" in [[Dragon Magazine]] #250 and, alternatively, in the [[Forgotten Realms]] splatbook "Sea of Fallen Stars".
Merfolk settlements are as as varied and widespread as the merfolk themselves.
* '''[[Ataropolis]]''' - An upstart mercantile city state that is undergoing rapid expansion and a cold war is brewing with a nearby kingdom of elves.
* '''Glacial Lake''' - arctic mer town
*''' Barony of Dagobus''' - religious abyssal mer empire. ocean canyon extends into continental crust, serves as raider outpost.
== Merfolk Culture & Technology ==
In Heroes of the Sea, merfolk stats look like this:
The Merfolk's aquatic environment has resulted in unque solutions to technical problems and independent evolution of their societies.
::Totally Water Adapted: A merfolk out of water is reduced to crawling, giving them a movement rate of 1, and after 1 hour out of water begins to fatally dehydrate, taking 2 damage per hour until they return to the water.
::Take double damage from Fire and are instinctively terrified of it.
Merfolk can easily attain neolithic technology with no special considerations. By learning metalurgy from land races, discovering it seperately on land, or by simply trading for alloys (like most human civilizations did), merfolk can acheive a fully realized bronze age civilization. Some other materials required for iron age technology are not practical for use in marine environments. Steel and iron rust within days, and for this reason merfolk have developed their own metallurgy tradition which has resulted in a distinct set of alloys and other materials.
* '''[https://en.wikipedia.org/wiki/Bronze Bronze]''' - Bronze is superior to iron and resists corrosion but is more expensive to produce.
== The Overcrowded Aquatic Humanoid Niche ==
* '''Stellite''' - Stellite is a silvery metal easily identifiable by its iridescent sheen which bends and splits light into different colors. It is as strong as steel, equally tough, highly heat resistant, and highly corrosion resistant. It was developed over several centuries, and is now is a staple metal for merfolk equipment. Stellite is an alloy of cobalt and chromium with higher quality varieties including small amounts of gold. The most exceptional and sought after type of Stellite uses a unique process to infuse magic into the metal. A merfolk sorcerer will perform a ritual to infuse a set of pearls with blue mana. The pearls are then dropped into the alloy while it is in a molten state. The pearls serve as a catalyst to allow mana to permeate the metal and improve its magic properties.
Merfolk are a pretty iconic "underwater race" in Western culture, but they're far from the only such creatures. And since D&D takes the "everything and the kitchen sink" approach to race design, well, merfolk kind of draw the short straw in that there have been a fuckton of races over the editions who can basically be described as "magical humanoids who live underwater". A ''short'' list of them, and only listing the ones that specifically live underwater rather than the "humanoids adapted to life on the coasts or at sea" like the various [[demihuman]] subraces from [[Environment Book Series|Stormwrack]], would include:
* '''[http://en.wikipedia.org/wiki/Orichalcum Aurichalcum]'''- Auricalcum is a rare and mysterious metal dug from out of Seamounts, undersea volcanos, and thermal vents. It has a golden or coppery color and it has similar mechanical properties to steel such as strength and toughness, but it is impervious to corrosion. This extremely valuable metal is highly desired for its mysteriously high magical conductivity. Armors made of Aurichalcum draw Magic into the metal and harmlessly away from the user. Armor crafted from Orichalcum costs +1000/+4000/+9000 gp more than normal for light/medium/heavy armor and is always considered to be of masterwork quality. Because of its magic resistant properties, the wearer of orichalcum armor gains a +1/+2/+3 bonus on saving throws made to resist spells, spell-like abilities and supernatural abilities. This bonus is further increased by half the armor's enhancement bonus (round down, min 0).
* [[Aquatic Elf|Aquatic Elves]], who are literally "elves, but underwater".
* [[Selkie]]s, aquatic fey who can shapeshift into the form of seals.
* [[Siren|Sirines]], which are literally [[nymph]]s of the sea.
* [[Pahari]], which are the [[Al-Qadim]] equivalent of merfolk, except they're a) able to transform into pure human and pure fish forms, and b) exclusively women.
* [[Triton]]s, which are either two-tailed merfolk or merfolk with legs depending on the edition.
* [[Nereid]]s, the ''actual'' oceanic [[nymph]] from Greco-Roman mythology.
* [[Shalarin]], fin-backed sea-people native to the [[Forgotten Realms]].
* [[Liminal]]s, which at least are supposed to be "half-merfolk".
* [[Sea Kin]], the specific [[Half-Fey]] born to aquatic fey like selkies, sirines and nereids.
* [[Aventi]], which are your stock "[[Atlantean]]s as humans who can breathe underwater and swim good" race.
* [[Koalinth]]s, which are aquatic [[hobgoblin]]s.
* [[Merrow]], which began as "[[ogre]]s, but live underwater".
* [[Scrag]]s, which are the [[troll]] counterpart to merrow.
* [[Malenti]], which are aquatic elves, but secretly sharks.
*[https://en.wikipedia.org/wiki/Byssus '''Byssus''']/[https://en.wikipedia.org/wiki/Sea_silk '''Sea Silk''']-strong fibers from mullosks that are immune to water degradation and can be woven into fabrics to make clothing, rope, nets, and other tools.
Considering that all of these - which aren't even accounting for the "aquatic [[beastfolk]] races like [[crabfolk]] or [[locathah]] - are able to actually get around on dry land and most of them are playable, and the poor merfolk look even more screwed over.
*'''Sharkskin''' - Leather made from the skin of sharks. it is very tough.
===Buildings And Cities===
===Gallery===
[[File:mercity.jpg|right|thumb|400px]]
<gallery>
[[File:The Forgotten Atlantis by firedudewraith.jpg|right|thumb|400px]]
Merman 1e.jpg|1e
Merfolk cities are often very densely constructed compared to land based races for a number of reasons. Roads can be very narrow by terrestrial standards because merfolk are able to use three dimensions for their streets. Sometimes the upper floors of buildings are conjoined across the streets which turns the streets into tunnels. Some cities have been built up over time so that tunnels have completely replaced streets in many areas.
Merman monster card.jpg|AD&D Monster Card
Merman MCV2.jpg|2e
Merman MM 2e.png
Merfolk 5e.png|5e
TWBTW palasha.png
</gallery>
Merfolk are able to contruct buildings much more efficiently than land races. They attach inflatable gas bags to a large building materials and lift them by filling the bag with air. Only a few workers are needed to position the piece. For this reason, gigantic buildings and monuments are common in merfolk cities.
== Pathfinder Merfolk ==
With a +2 in dexterity, constitution, and charisma with no stat minus, +2 natural armor, and unlike some amphibious races not drying up if they're on land, Merfolk are a fantastic race. The only problem? Sloooow on land. 5 feet move (15 with a trait- still half of everyone else). If you pick a class that gets a way to give them respectable movement and/or you just don't mind being the slowest one around, a solid choice.
Merfolk structures often incorporate unique materials and features which results in distinct a architectural style. Wooden buildings are uncommon due to the effect of woodworms. Instead, Merfolk make use of a variety of durable marine building materials:
They have a [[Drow]] equivalent '''Deep Merfolk''' race, grey-skinned merfolk who live in the lightless depths of the seafloor.
*'''Kelp''' - Many merfolk buildings are made by weaving living kelp into a hollow ball that floats in the water while anchored to ocean floor. There can be several rooms arrayed in a daisy chain, one above the other, all constructed from only a few plants.
<gallery>
*'''sea grass''' - Sea grass is used as a filler material in thatching and living sea grass is planted on the roofs of buildings as an anchor or decoration.
Merfolk B1.png
*'''Coral''' - Coral is tough easily workable, and abundant in tropical climates. It is used all over the aquatic world.
merfolk RoA4 1.png
*'''Stone''' - Used in alone or in combination with hydraulic cement, stone is one of the best materials for durablity.
merfolk RoA4 2.png
*'''hydraulic cement''' - hydraulic cement is a building material in use since ancient times and is known for its ability to harden underwater. hydralic cement is combined with sand or other materials to create concrete structures, or is used in mortar to create masonry buildings
merfolk RoA6 1.png
*'''Giant bones''' - The bones of giant sea creatures such as whales and sea serpents are and strong and durable enough to be excellent building materials
merfolk ARG.png
*'''giant shells''' - Some sea shell are large enough to be used by themselves as rooms in buildings. smaller ones are used in "shell masonry"
</gallery>
*'''wood''' - freshwater merfolk often use wood to build their structures, because woodworms do not live in freshwater.
'''Deep Merfolk'''
<gallery>
=== Agriculture ===
deep merfolk B5.jpg
The rich waters of most merfolk settlements allow for very productive fields of aquatic crops such as kelp, rice, water lilies, watercress, taro, lotus, waterspinach, wasabi, waterchestnuts, fish, and shellfish. Large enclosures serve as pastures for fish hatcheries. A typical farm consists of an oyster bed on the bottom of the sea floor, a canopy of kelp at the surface with columns reaching down to attach to the floor, and fish swimming in the water in the middle.
deep merfolk RoA4 1.png
deep merfolk RoA4 2.png
===Writing===
deep merfolk RoA4 3.png
Land races have developed many methods for storing information, and many of them function perfectly underwater.
deep merfolk RoA4 4.png
</gallery>
*engraving
*wax pencil
== Merfolk Equipment ==
===Weapons===
==Monstergirls==
Many weapons suffer reduced effectiveness under water due to hydrodynamic drag. Merfolk therefore use weapons that are specially designed to eliminate drag and increase ergonomics for submerged use. Some weapons are unchanged but the techniques for their use underwater is radically different.
Mermaids are naturally among the most common monstergirls. They have a very similar problem to [[centaurs]] though, in that if they're a nonhuman animal from the waist down, where's their vagina? Also like with the centaur, different approaches to "The Mermaid Problem" have been taken. Some give merfolk the genitalia of fish, thus having fertilization occur externally (sexual interactions with humans are typically of the oral variety in this case). Others instead have the fish part start ''just below'' the genitals, which would logically result in a weird hole through the middle of their bodies. Still others have the fish part start above where human genitals would be and just slap on a forward-facing human vagina at waist-height. The simplest approach taken is making mermaids limited shapeshifters, capable of transforming their tail into legs. This is typically paired with a duration limit or need to return to water within a limited time to stop them from being reduced to strictly better humans and keep them sea creatures.
! Name
! Damage
! Crit Threat
! Crit Damage
! Size
! Damage Type
! Skill Type
! Special
|-
| Partisan
| 2D6
| 19-20
| X2
| twohanded
| slashing/piercing
| Martial
|-
| Great Trident
| 1D12
| 20
| X3
| twohanded
| Piercing
| Martial
|-
| Mersarissa
| 1D12
| 20
| X3
| twohanded
| Piercing
| Exotic
| Reach
|-
| Chain Net
| 1D4
| 20
| X2
| onehanded
| slashing
| exotic
| see text
|-
| Katar
| 1d6
| 20
| X2
| onehanded
| slashing
| simple
|-
| Cestus
| 1d6
| 20
| X2
| one handed
| crushing
| Simple
|}<br style="clear: both; height: 0px;" />
*'''Partisan''' - A partisan is a pole-arm similar to a spear but it has a much larger spear point and prongs on either side of the blade. it could accurately be described as a sword on a pole.
On their page titled "The Mermaid Problem," [[TVTropes]] of all sites puts forth the clever idea of replacing the fish tail with a dolphin tail. This is brilliant for more reasons than that article seems to realize, since not only does it simplify a lot of the internal biology by making them fully-fledged mammals, but there's also the fact that dolphins are actually [[Slaanesh|notoriously]] [[rape|perverted]] in regards to sexual behavior, with individuals of both sexes often trying to bone dolphins and non-dolphins alike, and there being so much sex overall that the females of some species have evolved ''an additional pelvic orifice that exists for the sole purpose of sex''. On top of that, since it's hard to hold onto someone you're constantly thrusting into when you A) are floating around in the ocean, B) don't have arms, and C) can't coil around them like a snake or eel, dolphins of both sexes actually have ''MOTHERFUCKING PREHENSILE GENITALS''. Yeah, you're probably getting several ideas ''right now'', aren't you, you perv?
*'''Great trident''' - This trident has 3 large bladed points and is capable of delivering grievous wounds.
*'''Mersarissa''' - A very long spear for use in underwater army formations. it has a large blade and reach.
*'''Chain Net''' - A net made of fine chain links or cable instead of rope. it follows the same rules for a normal net but has a stronger break DC of 35, escape artist check of 25, DR 5, and 20 hit points. It has small barbs that cut a trapped creature as it struggles.
*'''Katar''' - A short sword that attaches to the forearm instead of being held by the handle
*'''Range weapon''': most range weapons have a range of 3d6 feet rather then there stated range and for every six feet there projectile travels they lose D4 damage. if the damage they inflict turns to 0, then the arrow arcs mid flight and points harmlessly to the ocean floor.
===Armor and Shields===
===MGE===
[[File:Scale mail detail.jpg|thumb|right|400px]]
It'd be more surprising if the [[Monster Girl Encyclopedia]] ''didn't'' have a mermaid mamono. They are portrayed as incurable romantics who yearn to find that special someone. They also have quite a family tree, with [[Merrow]] (their perverted cousins), Sea Bishops (mermaid [[cleric]]s of the sea goddess), Mersharks (aggressive shark-based mermaids), Unagi Joro (lamia-esque eel-maids from Zipangu) and even [[Selkie]]s (wereseals) making up part of the Mermaid class of mamono.
There are several considerations to make when using armor underwater, drag and buoyancy. Merfolk armors are usually form fitting and flexible. Medium and heavy armors usually use some form of buoyant material for padding such as kelp pods or cork. Shields are designed to have as little drag as possible when moving them laterally and also have small buoys distributed to the inner surface. Tower sields are extremelly rare in the underwater world because they are simply too unwieldy and the reduced danger from ranged weapons. They have been reduced to specialty applications.
*'''sharkskin leather armor''' - Basic leather armor has the same properties as land based leather armor.
*'''Padded''' - This padded armor uses aquatic fibers to give its wearer some protection.
*'''chain shirt''' - Chain shirts built by merfolk smiths tend to be tighter fitting than those on land to reduce drag.
*'''Scale mail''' - Scale mail is more popular with merfolk than chain because it has less drag.
*'''breastplate''' - Breast plates are very popular in in the underwater world for their ease of manufacture, good protection, and freedom of movement
*'''chain halberk'''
*'''Lorica Plumata''' - This armor is a combination of chainmail and scalemail. It consists of metal scales that are attached to a backing of tight fitting chainmail. It is expensive but gives excellent freedom of movement, low drag, and good protection.
*'''platemail'''
== Merfolk Magic ==
<center>
The Merfolk have a divergent tradition in the magical arts. Some marine spells accomplish the same objectives as their land counterparts, but in a different way.
* '''Merfolk Blood''' - Some types of Merfolk have blood that has vague magical properties. Evil races often wish to kill merfolk to harvest it. Merfolk blood has a number of uses depending on the source species.
* '''Spell Shell''' - Many merfolk wizards choose not use spellbooks. Instead they use magical sea shells that store spells in sound form rather than in writing. To memorize a spell for the day, a wizard listens to the song inside the spell shell. To add a spell to the shell, the wizard etches magical runes and symbols into a precious stone which is then placed into the shell. These stones are analogous to the more traditional paper that other races use to store their spells.
===Spells===
* '''Crush''' - creates magical water pressure in an area that crushes creatures in its area effect
* '''Shape Metal''' - shapes metal
* '''decompress''' - Decompresses the area around the target causing wracking pains in his joints and body
* '''Resonance''' - creates very intense sounds that resonate in the water, does.... something
* '''Freeze''' - Freeze the water around the target which traps them in a solid block of ice
* '''Salmons lessons'''- Fourth level druid spell, '''component''' vocal, focus, '''target'''-one creature, '''saving throw''' Will-'''Spell Resistance'''-No: '''effect''': target creature can now Enter (and breath if it has gills) either salt or fresh water depending on which version of the spell was cast. This spell affects all animals that live in water since with out the proper adaptations a animal will suffer damage for being in the wrong environment. Arcance Focus: A vial of fresh or salt water depending on which version of the spell is being cast.
===Familiars===
[[File:flyingfish.jpg|right|thumb|400px]]
*octopus +2 stealth
*flying fish +3 fly
*crab +2 fortitude saves
*lobster +1 natural armor
*salmon +3 swim
*sea anemone +3 Hp
*Tiny shark +3 perception in light
*Lanternfish+2 Perception in dark
*jelly fish +2 will
*mantis shrimp +2 Spot
*Carp (fresh water only)+2 jump
*temperate fish +2 acrobatics
*Tropical fish +2 initiative
*Sea Star +2 survival
*squid +2 sleight of hand
*Nautilus +2 diplomacy
== Merfolk Artifacts ==
Ancient and legendary items in the underwater world.
* '''Pearl Trident'''
* '''Bubble Band''' - This magical headband creates a bubble of breathable air around the head of the user. Merfolk use these bands to allow non water breathing individuals to freely travel underwater. The magic used to create these bands is a closely guarded secret.
[[File:Naga siren by arriva sama-d5beajs.jpg|thumb|right|300px]]
* '''Slithice's Net''' - This flawless orichalcum chain net glows with a blue light that radiates from the metal in long floating strands. it was given to an ancient hero of legend from the trove of ocean gods, and was intended for use against leviathans that were threatening their patron cities. When thrown, it magically expands to trap any target that is small size or larger. It is able to be thrown through water as if it had the same resistance as air. any creature trapped inside the net is effected by an anti magic field, prevented from teleporting, and is fixed to any adjacent surface. It has a +5 enchantment.
== Merfolk Religion ==
The merfolk worship some of the same gods as other races, but they also have their own unique racial pantheon.
=== Dagobus ===
Mega Outsider (Earth, Elemental, Evil, Extraplanar, Undead)
Alignment: Lawful Evil
Dagobus or Father Earth is the Merfolk god of the earth. Hydrothermal
vents in the earth's crust are sacred to Dagobus. Father Earth does
not solely draw upon the power of believers but has his own
independent power granted by both Malron and Nox.
'''Neutral Aspects'''': Earth, Iron, Fire, Power
'''Positive Aspects:''' Law, Passion, Art
'''Negative Aspects:''' Anger, Violence, Poison, Darkness, Death
==== Awakened Dagobus ====
''Around the sun dances a massive head of molten iron in a furious''
''orbit. This iron head constantly belches toxic gas and poison and''
''screamed obscenities and curses. A long wild mane of hair composed of''
''fire and magma whip back and forth across the great iron head and a''
''giant multitude of arms composed of earth and clay beat on upon''
''themselves and the head with furious activity.''
===== Combat =====
Before the Sea Mother's great treachery Father Earth once charged
relentlessly into battle with the firey rage of burning rock and
titanic earthquakes.
Dagobus's natural weapons as well as any weapons he wields are treated
as lawful-aligned, epic and evil-aligned for the purpose of overcoming
damage reduction.
==== Avatar of Dagobus ====
''A great big iron head with many arms that spits fire and poison''
''gas.''
Just an iron golem forged into a funny shape by worshippers of
Merfolk are mythological creatures that have the upper bodies of humans and the lower bodies of a marine animal, almost always a fish. They originated in medieval folklore as mermaids, creatures that would seduce blueballed sailors to drown them (mermen were invented sort of as an afterthought to explain procreation). They are prominently featured in MTG, RPGs, and even 40k had a minor aquatic race at one point. Creatures similar to merfolk can also be found in many videogames, such as the Zora from The Legend of Zelda, the Naga from Warcraft, and the Slithereen from Dota2.
Dungeons & Dragons and Pathfinder generally have given merfolk only lackluster attention, as their unique body configuration makes them to all practical purposes useless on your typical land-based campaign, but, if you add them into a "surfacers gone underwater" campaign (itself a rarity), they tend to be overpowered, as they are faster and don't need to worry about breathing underwater. D&D usually tries to push the Triton over the merfolk as a consequence, as Tritons at least can try to partake in both underwater and traditional campaigns.
Still, despite their issues, /tg/ has had a spattering of threads dedicated to merfolk over the years where it has discussed how an underwater civilization would develop, and many people have wished to use merfolk characters or merfolk cities in their campaign. Unfortunately, most settings have rules that are not conducive to using merfolk as player characters, fluff that does not include merfolk as a major power, and a lack of effort to describe a thriving merfolk civilization.
Racial Class & Level Limits: Fighter 12, Shaman 3, Cleric (Specialist priest of Eadro only) 7, Bard (Thief with Humanoid Bard kit, Female Only) 9
Available Kits: Tribal Defender, Oracle, Wandering Mystic
Natural Armor Class: 7
Swim Rate 18
No movement or attack penalties when in water.
Amphibious: Can breathe air and water.
Totally Water Adapted: A merfolk out of water is reduced to crawling, giving them a movement rate of 1, and after 1 hour out of water begins to fatally dehydrate, taking 2 damage per hour until they return to the water.
Take double damage from Fire and are instinctively terrified of it.
Weapion Proficiencies: Crossbow, Trident, Javelin
Nonweapon Proficiencies: Alertness, Animal Handling, Animal Lore, Animal Training (Fish), Bowyer/Fletcher, Danger Sense, Direction Sense, Gaming, Hunting, Local History, Mining, Religion, Survival (Aquatic)
Female merfolk also have the NWPs Artistic Ability (Shell Carving, Tapestry Weaving), Chanting, Poetry, Singing and Weaving.
In Sea of Fallen Stars, this variant statblock is given:
Merfolk are a pretty iconic "underwater race" in Western culture, but they're far from the only such creatures. And since D&D takes the "everything and the kitchen sink" approach to race design, well, merfolk kind of draw the short straw in that there have been a fuckton of races over the editions who can basically be described as "magical humanoids who live underwater". A short list of them, and only listing the ones that specifically live underwater rather than the "humanoids adapted to life on the coasts or at sea" like the various demihuman subraces from Stormwrack, would include:
Aquatic Elves, who are literally "elves, but underwater".
Selkies, aquatic fey who can shapeshift into the form of seals.
Pahari, which are the Al-Qadim equivalent of merfolk, except they're a) able to transform into pure human and pure fish forms, and b) exclusively women.
Tritons, which are either two-tailed merfolk or merfolk with legs depending on the edition.
Nereids, the actual oceanic nymph from Greco-Roman mythology.
Merrow, which began as "ogres, but live underwater".
Scrags, which are the troll counterpart to merrow.
Malenti, which are aquatic elves, but secretly sharks.
Considering that all of these - which aren't even accounting for the "aquatic beastfolk races like crabfolk or locathah - are able to actually get around on dry land and most of them are playable, and the poor merfolk look even more screwed over.
With a +2 in dexterity, constitution, and charisma with no stat minus, +2 natural armor, and unlike some amphibious races not drying up if they're on land, Merfolk are a fantastic race. The only problem? Sloooow on land. 5 feet move (15 with a trait- still half of everyone else). If you pick a class that gets a way to give them respectable movement and/or you just don't mind being the slowest one around, a solid choice.
They have a Drow equivalent Deep Merfolk race, grey-skinned merfolk who live in the lightless depths of the seafloor.
Mermaids are naturally among the most common monstergirls. They have a very similar problem to centaurs though, in that if they're a nonhuman animal from the waist down, where's their vagina? Also like with the centaur, different approaches to "The Mermaid Problem" have been taken. Some give merfolk the genitalia of fish, thus having fertilization occur externally (sexual interactions with humans are typically of the oral variety in this case). Others instead have the fish part start just below the genitals, which would logically result in a weird hole through the middle of their bodies. Still others have the fish part start above where human genitals would be and just slap on a forward-facing human vagina at waist-height. The simplest approach taken is making mermaids limited shapeshifters, capable of transforming their tail into legs. This is typically paired with a duration limit or need to return to water within a limited time to stop them from being reduced to strictly better humans and keep them sea creatures.
On their page titled "The Mermaid Problem," TVTropes of all sites puts forth the clever idea of replacing the fish tail with a dolphin tail. This is brilliant for more reasons than that article seems to realize, since not only does it simplify a lot of the internal biology by making them fully-fledged mammals, but there's also the fact that dolphins are actually notoriouslyperverted in regards to sexual behavior, with individuals of both sexes often trying to bone dolphins and non-dolphins alike, and there being so much sex overall that the females of some species have evolved an additional pelvic orifice that exists for the sole purpose of sex. On top of that, since it's hard to hold onto someone you're constantly thrusting into when you A) are floating around in the ocean, B) don't have arms, and C) can't coil around them like a snake or eel, dolphins of both sexes actually have MOTHERFUCKING PREHENSILE GENITALS. Yeah, you're probably getting several ideas right now, aren't you, you perv?
It'd be more surprising if the Monster Girl Encyclopediadidn't have a mermaid mamono. They are portrayed as incurable romantics who yearn to find that special someone. They also have quite a family tree, with Merrow (their perverted cousins), Sea Bishops (mermaid clerics of the sea goddess), Mersharks (aggressive shark-based mermaids), Unagi Joro (lamia-esque eel-maids from Zipangu) and even Selkies (wereseals) making up part of the Mermaid class of mamono.