TEXT: Caverns of the Merfolk
  Caverns of the Merfolk
  An Underwater Settlement
  An Underwater Settlement
  by Travis Legge
  by Travis Legge
  
  2
  CAVERNS OF THE MERFOLK
  Caverns of the Merfolk
  An Underwater Settlement
  Introduction: The merfolk are mysterious amphibious humanoids with unique cultures and 
  societies arrayed beneath the waves. Caverns of the Merfolk details a unique merfolk settle-
  ment that benefits from unusual magic practiced by the village seer. Through this magic, the 
  merfolk of Dragon’s Eye Cavern have developed tools for writing, crafting advanced tools, and 
  even forging weapons. The seer’s magic has also permitted limited trade with nearby surface 
  communities. This book contains a detailed view of Dragon’s Eye Cavern and the merfolk who 
  dwell there, which can be used in any Dungeons & Dragons setting.
  Cover Art: Some artwork © 2018 Quico Vicens-Picatto, used with 
  permission. All rights reserved.
  Cover Elements use artwork Designed by LuqueStock / Freepik
  Interior Art
  Courtesy WOTC p. 3
  By Brett Neufeld p.5
  by Kristen Collins p. 6
  by Matt Morrow p. 7
  Cartography by Dyson Logos
  by Travis Legge
  DUNGEONS & DRAGONS, D&D, Wizards of the Coast, Forgotten Realms, the dragon ampersand, and all 
  other Wizards of the Coast product names, and their respective logos are trademarks of Wizards of the Coast in 
  the USA and other countries.  
   
  This work contains material that is copyright Wizards of the Coast and/or other authors. Such material is used 
  with permission under the Community Content Agreement for Dungeon Masters Guild.  
   
  All other original material in this work is copyright [2019] by Travis Legge and published under the Community 
  Content Agreement for Dungeon Masters Guild.
  
  3
  BY TRAVIS LEGGE
  Dragon’s EyE CavErn 
  “Great attention gets paid to rainforests because of 
  the diversity of life there. Diversity in the oceans is 
  even greater.”
  — Sylvia Earle, Oceanographer
  Dragon’s Eye Cavern is a ready-made location for 
  use in your Dungeons & Dragons campaign. This 
  merfolk village can be set anywhere along the 
  coastline of any D&D setting. Unlike most merfolk 
  villages, Dragon’s Eye Cavern has developed magical 
  means to facilitate trade, commerce, and ease of 
  visitation with nearby surface dwellers. Whether the 
  inhabitants of this village are friend, foe, tense trading 
  partner, or temporary allies of convenience, everything 
  you need to incorporate this vibrant undersea locale 
  into your Dungeons & Dragons campaign is included 
  within these pages.
  The Village
  The information here details the village of Dragon’s 
  Eye Cavern as it is today. Some historical and cultural 
  information is provided within the descriptions of 
  the areas of this underwater settlement, but 
  much of the village’s history, politics, and 
  relationship with outsiders are left to the 
  Dungeon Master to determine. Use this location 
  as best fits your campaign.
  General Features
  All areas of Dragon’s Eye Cavern have the following 
  features unless otherwise noted in the room 
  description:
   
  Ceilings. The ceilings in each chamber are rough 
  stone and 30 feet high with stalactites hanging 
  from 5 to 15 feet from the ceiling at 
  all points.
   
  Floors. The floors are 
  smooth, worked stone. 
   
  Light. 
  Bioluminescent 
  dragon eye coral on 
  the walls and ceilings 
  provide bright light 
  throughout the 
  complex.
   
  Regional Effects. Sound is muffled and unclear 
  in the underwater cave. Any Wisdom (Perception) check 
  that relies solely on hearing is made at disadvantage. 
  Successfully understanding any spoken language 
  other than Aquan in the area requires a successful 
  DC 10 Wisdom (Insight) check for each sentence 
  spoken. Nonverbal languages such as thieves’ cant are 
  unaffected. 
   
  Spells requiring a verbal component also 
  require a successful DC 10 Constitution saving throw 
  in order to cast successfully. If the check is successful, 
  the spell is cast. If failed, the spell fails, and the 
  slot is wasted. Note that this check still applies to 
  creatures who are amphibious, under the effects of 
  runes of waterbreathing, or otherwise able to breathe 
  underwater.
   
  The water in each chamber can be made 
  breathable by surface folk through the activation of 
  runes of waterbreathing (see Appendix B: Magic Items) 
  in each area. If these runes are not active, creatures 
  who are unable to breathe underwater begin suffocating 
  as described in chapter 8 of the Player’s Handbook. 
  
  4
  CAVERNS OF THE MERFOLK
  1. Cave Entrance and Main Thoroughfare 
  A 20-foot wide cave mouth opens into a large 
  chamber with 45-foot high ceilings. The floor gently 
  ramps downward toward area 13. At the drop off to 
  area 13 the ceiling is 75 feet from the ground. This 
  area is a major thoroughfare and is often busy with 
  merfolk traveling back and forth between the various 
  districts of the cave. At the south end of the cave a 15 
  foot sheer cliff rises up to area 2. At any time of day or 
  night 3d10 merfolk are found in this region.
  2. Guard Overwatch 
  This cliff too looks down over the main thoroughfare 
  and serves as a central security post for the village. 
  Six merfolk guards are posted here, watching the 
  thoroughfares and tunnels from the high vantage. 
  There is a large conch shell mounted on the wall here 
  that can be blown in case of emergency. When the 
  conch is blown, the alarm can be heard throughout 
  the village.
  3. Hallway 
  The walls of this hallway contained luminescent 
  murals depicting the history of the Dragon’s Eye 
  Merfolk. Close inspection reveals that the murals 
  are not painted, but rather crafted from carefully 
  cultivated bioluminescent flora. The murals reveal a 
  challenging past for the merfolk of the village, with 
  hunting and gathering not always being sufficient to 
  meet the settlement’s needs. With the arrival of a seer, 
  depicted with a glowing halo around their head, the 
  villagers learned new skills and began to prosper.
  4. The Slaughtered Dolphin 
  This corridor is the main dining and social hall of 
  the village. Circular tables made from giant clamshells 
  turned upside down and topped with flat stone are 
  placed throughout the hall for the merfolk to enjoy 
  a meal and conversation. The cuisine served at the 
  Slaughtered Dolphin is a mix of fish, crustacean, 
  seaweed, and rice. Meal prices are double those listed 
  in the Player’s Handbook Chapter 5.
  
  5
  BY TRAVIS LEGGE
  When closed for business, the inn’s doors can be 
  locked. A creature proficient with thieves’ 
  tools can pick these lock with a successful 
  DC 15 Dexterity check. The keys to these 
  locks are carried by Sharlyn Ahlorsath (she/
  her triton veteran), the owner of the Slaughtered 
  Dolphin. A spare set of keys is also kept in the kitchen. 
  NPC Alignments
  The NPCs presented throughout 
  this section are not given an 
  alignment. This is deliberately 
  left to the Dungeon Master to 
  determine, depending on the role 
  they wish Dragon’s Eye Cavern to fill 
  in their campaign. A friendly trading 
  partner would likely have mostly good 
  alignments, whereas an enemy state 
  may lend itself to more evil alignment. Use 
  whatever suits your game best.
  5. Guesthouse 
  This area is the sole guest quarters at the 
  Slaughtered Dolphin. Due to recent increases 
  in trade with surface folks, the innkeeper is seeking 
  new and innovative ways to modify the room for dry 
  sleeping, so far with little luck.
  6. Kitchen 
  This is where the food served at the Slaughtered 
  Dolphin is prepared and stored.
  Treasure. This area contains food supplies and 
  trade goods worth 100 gp. If the kitchen is completely 
  raided there are enough supplies to create 2 sets of 
  cook’s utensils.
  7. Sharlyn’s Apartment 
  This chamber is Shalryn’s residence. The room 
  contains a comfortable clamshell bed with a mattress 
  made of living sponge. At the foot of the bed, Sharlyn 
  keeps a locked chest, the key to which is on her 
  person. Along the north wall is a dresser crafted from 
  coral.
  Treasure. A creature proficient with thieves’ tools 
  can pick the lock on the chest with a successful DC 
  17 Dexterity check. The chest contains 5 black pearls 
  worth 500 gp each, a set of leatherworker’s tools, a 
  gold dragon comb with red garnets set as eyes valued 
  at 750 gp, and a pole of angling.
  8. Hunter’s 
  Row
  The west end of 
  this chamber opens into a 
  large area where a limestone 
  statue depicting three merfolk 
  spearing a shark stands in the 
  center of the chamber before the east entrance to the 
  Slaughtered Dolphin.
  9. Stairwell Tunnel 
  This tunnel leads down to the lower level of the 
  village, sloping downward 60 feet over the course 
  of its length. Stairs have been carved into the floor 
  in recent months to accommodate visiting surface 
  dwellers.
  
  6
  CAVERNS OF THE MERFOLK
  10. Durdona’s Home 
  This chamber is the home of Durdona (she/her 
  merfolk archdruid) the village seer. Though the place 
  looks to be largely overrun by underwater plants, in 
  truth these are mostly cover for Durdona’s personal 
  guards, an awakened coral and a dragon’s eye 
  kelpie.
  11. Durdona’s workshop 
  This is where Durdona works her enchantments 
  and rituals. This area is filled with various druidic 
  tools and magical trinkets.
  Treasure. Investigating this area uncovers 20 
  sprigs of mistletoe, 20 totems, 5 wooden staves, 20 
  yew wands, 2 sets of Alchemist’s supplies, 2 sets of 
  jeweler’s tools, a set of weaver’s tools, several art 
  objects (a brass mug with jade inlay, bronze crown, 
  large gold bracelet, gold bird cage with electrum 
  filigree, gold ring set with bloodstones) worth 750 gp 
  each and a chaotic neutral sword of answering
  12. Jewelers Shop
  This junction is the connection between the upper 
  and lower halves of the cave network. It is also home 
  to the Pearlescent Dream, a jewelry and trinket shop, 
  run by Alon (he/him merfolk spy). Alon will pay 75% 
  of the listed price for gemstones and jewels, and has 
  jewelry for sale containing gemstones and jewels, 
  as well as jewelry listed as art objects at a value up 
  to 1,000 gp as listed in Chapter 7 of the Dungeon 
  Master’s Guide. In addition, Alon carries the 
  following magic items, which he is willing to sell at the 
  prices listed on the table below.
  Item
  Base Price
  Source
  Amulet of Health
  4,000 gp
  Dungeon Master’s 
  Guide
  Amulet of Proof against 
  Detection and Location
  400 gp
  Dungeon Master’s 
  Guide
  Bag of Holding
  400 gp
  Dungeon Master’s 
  Guide
  Bowl of Commanding 
  Water Elementals
  4,000 gp
  Dungeon Master’s 
  Guide
  Brooch of Shielding
  400 gp
  Dungeon Master’s 
  Guide
  Candle of the Deep
  150 gp
  Xanathar’s Guide to 
  Everything
  Chime of Opening
  4000 gp
  Dungeon Master’s 
  Guide
  Circlet of Human 
  Perfection
  600 gp
  Waterdeep Dungeon 
  of the Mad Mage
  Clockwork Amulet
  50 gp
  Xanathar’s Guide to 
  Everything
  Moodmark Paint
  100 gp
  Guildmasters’ Guide 
  to Ravnica
  Pole of Angling
  100 gp
  Xanathar’s Guide to 
  Everything
  Ring of Regeneration
  20,000 gp
  Dungeon Master’s 
  Guide
  Spell Gem (Topaz)
  60,000 gp
  Out of the Abyss
  Talking Doll
  100 gp
  Xanathar’s Guide to 
  Everything
  Haggling. A character attempting to purchase 
  any item from Alon can try to haggle to reduce the 
  price. This requires the character to make a DC 15 
  Charisma (Persuasion) check. If the roll succeeds, 
  the price is reduced by 25%. If the check fails by more 
  than 10, however, Alon becomes annoyed and raises 
  the asking price by 25%.
  Attacking Alon or being caught attempting to rob 
  the store immediately sends a silent alarm, which 
  informs the merfolk guards in area 20, who send 4 
  merfolk guards to investigate. These guards arrive in 
  3 rounds.
  13. Village Market 
  This is a massive marketplace where the merfolk of 
  Dragon’s Eye Cavern sell their various wares. On any 
  given day there are 20-30 shops open in simple stalls. 
  Each shop is staffed by 1-2 merfolk and any time of 
  day or night 3d10 merfolk are found shopping and 
  
  7
  BY TRAVIS LEGGE
  browsing in this region. The market is patrolled by 6 
  merfolk guards at all times, who travel in pairs. Any 
  non-livestock item found in Chapter 5 of the Player’s 
  Handbook can be purchased here, and much of it 
  is sold at the listed price. Anything made of metal, 
  designed to make fire, or containing elements that 
  would be spoilt by immersion underwater are 150% 
  the listed price.
  14. Warehouse 
  This chamber rises 35 feet above the village market 
  and is used as communal storage by the various 
  shopkeepers who ply their trade in the marketplace. 
  When a stall closes for the day, the owner takes their 
  stock to a private chest in this chamber.
  Treasure. In total, this space contains 25,000 gp 
  worth of trade goods and adventuring supplies.
  15. South entrance 
  This area is the southern entrance to the village and 
  is watched over by two merfolk guards.
  16. Tunnel Junction 
  This tunnel connects the main thoroughfare to Shell 
  City. A narrow, 5-foot wide corridor offers a shortcut 
  between the two areas but is rarely used by adult 
  merfolk. Children and teens, however, frequently make 
  use of this means of travel.
  17. Shell City 
  This area, named for the massive seashell 
  construction used in the small living quarters here, is 
  home to the majority of the lower-class population of 
  the village. Those who are not exceptionally skilled 
  hunters, have no real trade to speak of, and are not 
  able to grasp magic generally make their home in this 
  region. The merfolk who live here earn their living as 
  manual laborers or guards. A depression in the north 
  end of this section leads to an underwater passage 
  out of the caverns and into the sea. To the northeast, a 
  narrow tunnel leads down to area 18, the Lower Villa.
  18. Lower Villa 
  This depression is where the poorest members of 
  the village make their homes in lean-tos and makeshift 
  shacks. They scrape by on whatever they can 
  scrounge, beg, borrow, or earn as day laborers.
  
  8
  CAVERNS OF THE MERFOLK
  19. Lower Promenade 
  This tunnel runs through the stone beneath area 1, 
  connecting area 12 to area 20. The walls, floor, and 
  ceiling of this 10 x 10 roughhewn tunnel are lined with 
  luminescent algae in a full spectrum of colors, giving 
  the hallway the appearance of an impressionistic 
  painting or an exceptionally vibrant sunset. 
  20. Guardhouse
  This is the armory where the village guard keeps 
  weapons and armor. It is staffed by 6 merfolk guards 
  at all times.
  Treasure. In addition to the weapons and armor 
  actively being worn and used by the guard, the 
  guardhouse contains 10 tridents, 10 breastplates, and 
  10 shields.
  21. Landlord’s Lodge 
  This is the residence of Marlin (he/him merfolk), 
  the landlord of the Wave’s Break Complex. Marlin is a 
  handy and skilled, but somewhat gruff.
  Treasure. Marlin keeps a set of thieves’ tools and a 
  set of tinker’s tools in his apartment as well as four 
  sets of common clothes and a cloak of many fashions.
  22. Private Apartments 
  This section contains two small private apartments, 
  maintained by Dar (he/him merfolk salvager) and 
  Sishel (she/her merfolk salvager), two of the most 
  prominent hunters of the settlement.
  23. Common Living 
  This is a common living space separated by woven 
  seaweed curtains for privacy. 20 merfolk make their 
  homes here.
  24. Concha’s Home 
  The home of Concha (she/her merfolk) the smith. A 
  collection of sculptures and art objects are displayed 
  along the walls of the chamber, many of which were 
  crafted by the merfolk.
  Treasure. The sculptures throughout this area 
  depict all manner of sea life. Some are made from 
  stone, some from worked metal, and some from coral. 
  The various sculptures are worth a total of 7,500 gp. 
  In addition to the art objects, there is an unlocked 
  chest containing 3 sets of common clothing, 2 sets of 
  fine clothing, and 5,000 gp in various gemstones and 
  jewels.
  25. The Coldforge Smithy
  This 30-foot high chamber is used for crafting 
  tools, shields, and weapons. It contains a stone forge 
  and equipment for metalworking, stone carving, and 
  leatherworking. The forge can be operated normally 
  thanks to magical intervention by Durdona which 
  leaves this chamber dry. Pipes worked into the cave 
  wall serve as a chimney that leads the smoke from the 
  forge up to the surface.
  
  9
  BY TRAVIS LEGGE
  appEnDix a: nEw CrEaturEs
  The following creatures are found in Dragon’s Eye 
  Cavern.
  Awakened Coral 
  Huge plant, unaligned
  Armor Class 13 (Natural Armor)
  Hit Points 59 (7d12 + 14)
  Speed 20 ft., swim 20 ft. 
  STR
  DEX
  CON
  INT
  WIS
  CHA
  19(+4)
  6 (-2)
  15 (+2)
  10 (+0)
  10 (+0)
  7 (-2)
  Damage Resistances Bludgeoning, Fire, Piercing.
  Senses Passive Perception 10
  Languages Any one language known by its creator
  Challenge 2 (450 XP)
  False Appearance. While the coral remains motionless, it is 
  indistinguishable from normal coral.
  Limited Amphibiousness. The coral can breathe air and water, 
  but it needs to be submerged at least once every  hour to 
  avoid suffocating..
  Actions
  Scratch. Melee Weapon Attack: +6 to hit, reach 10 ft., one 
  target. Hit: 14 (3d6+3) slashing damage.
  Dragon’s Eye Kelpie
  Medium plant, unaligned
  Armor Class 14 (Natural Armor)
  Hit Points 67 (9d8 + 27)
  Speed 10 ft., swim 30 ft. 
  STR
  DEX
  CON
  INT
  WIS
  CHA
  14(+2)
  14(+2)
  16 (+3)
  7 (-2)
  12 (+1)
  7 (-2)
  Skills Perception +3.
  Damage Resistances Bludgeoning, Fire, Piercing
  Condition Immunities Blinded, Deafened, Exhaustion
  Senses Blindsight 60 ft., Passive Perception 13
  Languages Common, Sylvan
  Challenge 4 (1,100 XP)
  Amphibious. The kelpie can breathe air and water.
  False Appearance. While the kelpie remains motionless in its 
  true form, it is indistinguishable from normal seaweed.
  Actions
  Multiattack. The kelpie makes two slam attacks.
  Slam. Melee Weapon Attack: +4 to hit, reach 10 ft., one target. 
  Hit: 11 (2d8+2) piercing damage. If the target is a Medium or 
  smaller creature, it is grappled (escape DC 12).
  Drowning Hypnosis. The kelpie chooses one humanoid it can 
  see within 150 feet of it. If the target can see the kelpie, the 
  target must succeed on a DC 11 Wisdom saving throw or be 
  magically charmed while the kelpie maintains concentration, up 
  to 10 minutes (as if concentrating on a spell).
  The charmed target is incapacitated, and instead of holding its 
  breath underwater, it tries to breathe normally and immediately 
  runs out of breath, unless it can breathe water.
  If the charmed target is more than 5 feet away from the kelpie, 
  the target must move on its turn toward the kelpie by the 
  most direct route, trying to get within 5 feet. It doesn’t avoid 
  opportunity attacks.
  Before moving into damaging terrain, such as lava or a pit, and 
  whenever it takes damage from a source other than the kelpie 
  or drowning, the target can repeat the saving throw. A charmed 
  target can also repeat the saving throw at the end of each of its 
  turns. If the saving throw is successful, the effect ends on it.
  A target that successfully saves is immune to this kelpie’s 
  hypnosis for the next 24 hours.
  
  10
  CAVERNS OF THE MERFOLK
  Merfolk
  Medium humanoid (merfolk), any alignment
  Armor Class 11
  Hit Points 11 (2d8 + 2) 
  Speed 10 ft., swim 40 
  STR
  DEX
  CON
  INT
  WIS
  CHA
  10(+0)
  13 (+1)
  12 (+1)
  11 (+0)
  11 (+0)
  12 (+1)
  Skills Perception +2
  Senses Passive Perception 12
  Languages Aquan and any one language (usually Common)
  Challenge 1/8 (25 XP) 
  Amphibious. The merfolk can breathe air and water.
  Actions
  Trident. Melee or Ranged Weapon Attack: +2 to hit, reach 5 ft., 
  or range 20/60 ft., one target. Hit: 3 (1d6) piercing damage, 
  or 4 (1d8) piercing damage if used with two hands to make a 
  melee attack.
  Merfolk Archdruid 
  Medium humanoid (merfolk), any alignment
  Armor Class 16 (Hide Armor, Shield)
  Hit Points 132 (24d8 + 24)
  Speed 10 ft., swim 40 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  10 (+0)
  14 (+2)
  12 (+1)
  12 (+1)
  20 (+5)
  11 (+0)
  Saving Throws INT +5, WIS +9
  Skills Medicine +9, Nature +5, Perception +9
  Senses Passive Perception 19
  Languages Aquan, Druidic plus any two languages
  Challenge 12 (8,400 XP)
  Amphibious. The merfolk can breathe air and water.
  Spellcasting. The merfolk archdruid is an 18th-level spellcaster. 
  Its spellcasting ability is Wisdom (spell save DC 17, +9 to hit 
  with spell attacks). It has the following druid spells prepared:
  Cantrips (at will): druidcraft, mending, mold earth, shape 
  water
  1st level (4 slots): animal friendship, create or destroy water, 
  cure wounds, speak with animals
  2nd level (3 slots): animal messenger, beast sense, lesser 
  restoration
  3rd level (3 slots): dispel magic, speak with plants, water 
  breathing
  4th level (3 slots): polymorph, stone shape, stoneskin, watery 
  sphere
  5th level (3 slots): commune with nature, mass cure wounds, 
  tree stride
  6th level (1 slot): heal, heroes’ feast, move earth
  7th level (1 slot): regenerate
  8th level (1 slot): tsunami
  9th level (1 slot): shapechange
  Actions
  Trident. Melee or Ranged Weapon Attack: +4 to hit, reach 5 ft., 
  or range 20/60 ft., one target. Hit: 3 (1d6) piercing damage, 
  or 4 (1d8) piercing damage if used with two hands to make a 
  melee attack.
  Change Shape (2/Day). The archdruid magically polymorphs 
  into a beast or elemental with a challenge rating of 6 or less 
  and can remain in this form for up to 9 hours. The archdruid 
  can choose whether its equipment falls to the ground, melds 
  with its new form, or is worn by the new form. The archdruid 
  reverts to its true form if it dies or falls unconscious. The 
  archdruid can revert to its true form using a bonus action on its 
  turn.
  While in a new form, the archdruid retains its game statistics 
  and ability to speak, but its AC, movement modes, Strength, 
  and Dexterity are replaced by those of the new form, and it 
  gains any special senses, proficiencies, traits, actions, and 
  reactions (except class features, legendary actions, and lair 
  actions) that the new form has but that it lacks. It can cast its 
  spells with verbal or somatic components in its new form.
  The new form’s attacks count as magical for the purpose of 
  overcoming resistances and immunity to nonmagical attacks.
  
  11
  BY TRAVIS LEGGE
  Merfolk Guard 
  Medium humanoid (merfolk), any alignment
  Armor Class 17 (Breastplate, Shield)
  Hit Points 11 (2d8 + 2) 
  Speed 10 ft., swim 40 
  STR
  DEX
  CON
  INT
  WIS
  CHA
  13(+1)
  12 (+1)
  12 (+1)
  10 (+0)
  11 (+0)
  10 (+0)
  Skills Perception +2
  Senses Passive Perception 12
  Languages Aquan and any one language (usually Common)
  Challenge 1/8 (25 XP) 
  Amphibious. The merfolk can breathe air and water.
  Actions
  Trident. Melee or Ranged Weapon Attack: +3 to hit, reach 5 ft., 
  or range 20/60 ft., one target. Hit: 4 (1d6+1) piercing damage, 
  or 5 (1d8+1) piercing damage if used with two hands to make a 
  melee attack.
  Merfolk Salvager 
  Medium humanoid (merfolk), any alignment
  Armor Class 12
  Hit Points 22 (4d8+4)
  Speed 10 ft., swim 40 
  STR
  DEX
  CON
  INT
  WIS
  CHA
  12(+1)
  14 (+2)
  12 (+1)
  11(+0)
  10 (+0)
  13 (+1)
  Saving Throws DEX +4, INT +2
  Skills Athletics +3, Perception +2, Stealth +4
  Senses Passive Perception 12
  Languages Aquan, Common
  Challenge 1 (200 XP)
  Amphibious. The merfolk can breathe air and water.
  Actions
  Multiattack. The salvager makes two attacks with its coral 
  rapier.
  Coral Rapier. Melee Weapon Attack: +4 to hit, reach 5 ft., or 
  range 20/60 ft., one target. Hit: 6 (1d8+2) piercing damage.
  Inject Toxin (2/Day). Melee Weapon Attack: +4 to hit, reach 
  5 ft., one target. Hit: 6 (1d8 + 2) piercing damage, and the 
  creature must succeed on a DC 12 Constitution saving throw or 
  be paralyzed until the end of its next turn.
  
  12
  CAVERNS OF THE MERFOLK
  Merfolk Spy 
  Medium humanoid (merfolk), any alignment
  Armor Class 12
  Hit Points 27 (6d8)
  Speed 10 ft., swim 40 
  STR
  DEX
  CON
  INT
  WIS
  CHA
  10(+0)
  15 (+2)
  10 (+0)
  12(+1)
  14 (+2)
  16 (+3)
  Skills Deception +5, Insight +4, Investigation +5, Perception +6, 
  Persuasion +5, Sleight of Hand +4, Stealth +4
  Senses Passive Perception 16
  Languages Aquan and any two languages
  Challenge 1 (200 XP)
  Amphibious. The merfolk can breathe air and water.
  Cunning Action. On each of its turns, the spy can use a bonus 
  action to take the Dash, Disengage, or Hide action.
  Sneak Attack (1/Turn). The spy deals an extra 7 (2d6) damage 
  when it hits a target with a weapon attack and has advantage 
  on the attack roll, or when the target is within 5 feet of an ally 
  of the spy that isn’t incapacitated and the spy doesn’t have 
  disadvantage on the attack roll.
  Actions
  Multiattack. The spy makes two melee attacks.
  Trident. Melee or Ranged Weapon Attack: +2 to hit, reach 5 ft., 
  or range 20/60 ft., one target. Hit: 3 (1d6) piercing damage, 
  or 4 (1d8) piercing damage if used with two hands to make a 
  melee attack.
  Hand Crossbow. Ranged Weapon Attack: +4 to hit, range 
  30/120 ft., one target. Hit: 5 (1d6 + 2) piercing damage.
  Triton Veteran
  Medium humanoid (merfolk), any alignment
  Armor Class 17 (Breastplate, Shield)
  Hit Points 58 (9d8 + 18)
  Speed 30 ft., swim 30 
  STR
  DEX
  CON
  INT
  WIS
  CHA
  17(+3)
  13 (+1)
  15 (+2)
  10 (+0)
  11 (+0)
  10 (+0)
  Skills Athletics +5, Perception +2
  Senses Passive Perception 12
  Languages Aquan and any one language (usually Common)
  Challenge 3 (700 XP)
  Amphibious. The triton can breathe air and water.
  Innate Spellcasting. The triton’s innate spellcasting ability is 
  Charisma (spell save DC 10, +2 to hit with spell attacks). It 
  can innately cast the following spells:
  1/day: fog cloud, gust of wind, wall of water.
  Emissary of the Sea. The triton can communicate simple ideas 
  with beasts that can breathe water. They can understand 
  the meaning of the triton’s words, though the triton has no 
  special ability to understand them in return.
  Guardians of the Depths. The triton has resistance to cold 
  damage and ignores any of the drawbacks caused by a deep, 
  underwater environment.
  Actions
  Multiattack. The veteran makes two melee attacks.
  Trident. Melee or Ranged Weapon Attack: +5 to hit, reach 5 ft., 
  or range 20/60 ft., one target. Hit: 6 (1d6+3) piercing damage, 
  or 7 (1d8+3) piercing damage if used with two hands to make a 
  melee attack.
  Heavy Crossbow. Ranged Weapon Attack: +3 to hit, range 
  100/400 ft., one target. Hit: 6 (1d10 + 1) piercing damage.
  
  13
  BY TRAVIS LEGGE
  appEnDix B: nEw MagiC itEMs
  The following magic items are found in Dragon’s 
  Eye Cavern.
  Rune of Waterbreathing
  Wondrous Item, rare
  This magical rune must be carved into a permanent, 
  immobile fixture such as a wall, floor, or ceiling. It may 
  then be activated by touching the rune and speaking 
  the command word. When activated, the rune grants 
  the effect of the water breathing spell to all creatures 
  within 120 feet of the rune. Creatures who leave the 
  affected area no longer benefit from the rune’s magic. 
  Once activated, a rune of waterbreathing remains 
  active until deactivated by touching the rune and 
  speaking the command word.
  If the rune is destroyed or defaced by dealing 4 or 
  more hit points of damage to the surface where it is 
  carved, its magic ceases to function.
  
  appEnDix C: Map
  
SOURCE: textdata/thevault/Dungeons & Dragons [multi]/5th Edition (5e)/3rd Party/Travis Legge/Travis Legge - Caverns of the Merfolk v1.0.pdf