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  Alister Konzegel's Field Guide Vol. II
  Aquatic Terrors
  Within the pages of this field guide are a handful of eerie and unusual water-dwelling or water-adjacent creatures inspired by
  weird animals from our own plane... See through the illusions of the arcanelure anglerfish; recoil from the acidic backsplash of the
  giant nudibranch; flee before the pharyngeal jaws of the moray dragon drag you down its gullet; and much more! 
  10 New Monsters for Dungeons & Dragons 5th Edition. 
  by Zeke Gonzalez 
  cover art DMsGuild Creator Resources 
   
  DUNGEONS & DRAGONS, D&D, Wizards of the Coast, Forgotten Realms, the dragon ampersand, Player’s Handbook, Monster
  Manual, Dungeon Master’s Guide, D&D Adventurers League, 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. All characters and their distinctive likenesses are
  property of Wizards of the Coast. This material is protected under the copyright laws of the United States of America. Any
  reproduction or unauthorized use of the material or artwork contained herein is prohibited without the express written permission
  of Wizards of the Coast.
  ©2016 Wizards of the Coast LLC, PO Box 707, Renton, WA 98057-0707, USA. Manufactured by Hasbro SA, Rue Emile-
  Boéchat 31, 2800 Delémont, CH. Represented by Hasbro Europe, 4 The Square, Stockley Park, Uxbridge, Middlesex, UB11 1ET,
  UK.
  1
  Alister Konezegel's Field Guide Vol. II
  
  Contents
  3
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  4
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  4
  5
  6
  6
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  10
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  Introduction .......................................................................
  Citations .............................................................................................
  Tips for the DM .................................................................................
  Aquatic Terrors ..................................................................
  Arcanelure Anglerfish .....................................................................
  Cookiecutter Shark ..........................................................................
  Giant Fisher Spider .........................................................................
  Giant Nudibranch .............................................................................
  Kelp Blight .........................................................................................
  Merfolk Prismbringer ......................................................................
  Moray Dragon ...................................................................................
  Rahab ..................................................................................................
  Scorpionfish Devil .........................................................................
  Winter Toad .....................................................................................
  Acknowledgements .......................................................
  Works Cited ..........................................................................
  Looking For Liches? ....................................................
  Monsters by CR .................................................................
  2
  Alister Konezegel's Field Guide Vol. II
  
  Introduction
  “T
  he calm placidity of the open ocean
  is a lie. Beneath the surface of the
  gently rolling waves and hiding
  amongst the swaying kelp lies a
  world of unspeakable terror and
  violence. Vicious creatures race
  through the water to rend the flesh
  of their prey; stealthy monsters lie in wait within secret
  places for an opportunity to strike; the living feast upon both
  the living and the dead with reckless abandon. Despite
  beautiful sunsets and the soothing salty air, the sea deceives
  with every exhalation of water striking its sandy shores. Take
  care never to underestimate the inhabitants of the sea, for
  they will not hesitate to tear apart the unwary or the overly
  confident..."
  -A.Z.Z. Konezegel, The Traveler's Guide to Tal'tura, Fourth
  Edition
  Alister Konezegel's Field Guide Volume II: Aquatic Terrors
  is a supplement containing 10 monsters designed for D&D
  5th Edition. These monsters use rules, spells, and concepts
  from the Wizards of the Coast’s D&D 5th Edition and are
  intended to supplement the Ghosts of Saltmarsh adventures.
  This bestiary is a collection of new aquatic monsters
  inspired by scientific literature. The stat blocks and citations
  were were first released on my twitter account
  @FantasyEcology, where you can find more monsters under
  #ScienceDnD and in Volume I of Alister's Field Guide:
  Monstrous Arthropods. And remember, if you seek the truly
  bizarre and the deeply terrifying, look no further than
  beneath the waves...
  Citations
  This field guild includes numerical references to the scientific
  literature which inspired these monsters. These references
  will look like this: (#). The number inside the parenthesis
  refers to a specific title from the Works Cited. I recommend
  the entries in this Works Cited section as further reading on
  the science of aquatic animals and the strange world of the
  open ocean. I hope you find these readings as fascinating as I
  do!
  Tips for the DM
  As with any supplement, Alister Konezegel's Field Guide
  Volume II: Aquatic Terrors should be adapted to work for
  your group. If you don’t like the way a monster works, please
  feel free to change it. Adjust the hit points, damage, abilities,
  spells, and lore of these creatures to suit your games and
  your players. For example, if you want to use a monster, but
  think that its ability to impose certain conditions on the
  characters won't be fun for your group, instead have it deal
  extra damage or give it a new trait!
  To deliver an optimum experience for your players, it is
  best to read the stat blocks of the monsters you intend to use
  in full before attempting to run them. There are spells,
  attacks, and abilities that you need to understand in advance
  to run a fun and effective encounter.
  Have fun using these monsters! It was highly enjoyable to
  create these creatures and set them loose on my own players,
  and I hope that you can share in that experience!
  3
  Alister Konezegel's Field Guide Vol. II
  
  Aquatic Terrors
  Arcanelure Anglerfish
  Arcanelure anglerfish are abominably large and rotund fish.
  Their gaping jaws are filled with several rows of needle-thin
  and razor-sharp teeth. Emerging from their forehead is a
  fleshy tendril bearing a glowing light (the arcane focus for
  their illusory magic). Hanging from the enormous body of the
  female are the tiny males, sexual parasites which bite and
  fuse to the female's enormous form (7).
  Astral Traveler. Ordinary anglerfish are transformed into
  these creatures by a mindflayer lich who dwells in the Eternal
  Spirals, a titan's corpse which is flooded by the Astral Sea.
  This ancient being experiments with magic in the hopes of
  creating a 10th level spell, creating a host of unusual beasts
  like the arcanelure anglerfish in the process.
  Cookiecutter Shark
  The cookiecutter shark is a small but fearsome beast most
  readily identified by its brown, wrinkled sharkskin and maw
  of nearly transparent teeth. With a single bite, the
  cookiecutter shark is capable of removing perfectly circular
  plugs of flesh from its victims (6). Sometimes an unlucky
  victim finds they have lost a finger or toe to a well-timed bite
  by one of these fish, which swim quickly away after obtaining
  their meal.
  Gnomesbane. Sea-focused artificers and tinkerers often
  curse these sharks and refer to them as "Gnomesbane" due
  to the fact that cookiecutter sharks have been known to
  assault apparatuses of kwalish and bring underwater
  explorations in clockwork devices to a screeching halt.
  4
  Arcanelure Anglerfish
  Huge monstrosity, unaligned
  Armor Class 13 (natural armor)
  Hit Points 126 (11d12 + 55)
  Speed swim 50 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  23 (+6) 20 (+5) 21 (+5) 1 (-5) 13 (+2) 5 (-3)
  Skills Perception +5, Stealth +8
  Senses darkvision 60 ft., blindsight 10 ft., passive
  Perception 15
  Challenge 5 (1,800 XP)
  Innate Spellcasting. The anglerfish's innate
  spellcasting ability is Wisdom (spell save DC 13).
  She can innately cast the following spells, requiring
  no components:
  At will: minor image
  3/day: silent image
  Underwater Camoflage. The anglerfish has advantage
  on Dexterity (Stealth) checks made while
  underwater.
  Water Breathing. The anglerfish can breathe only
  underwater.
  Attached Mates (1/Day). When a creature touches
  the anglerfish or hits her with a melee attack, the
  anglerfish may use her reaction to shake off her
  parasitic mates, summoning a swarm of quippers.
  The swarm appears in an unoccupied space within
  5 feet of the summoner and act as an ally of the
  summoner.
  Actions
  Bite. Melee Weapon Attack: +9 to hit, reach 5 ft.,
  one target. Hit: 22 (3d10 + 6) piercing damage.
  Cookiecutter Shark
  Small beast, unaligned
  Armor Class 13
  Hit Points 60 (17d6)
  Speed swim 30 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  13 (+1) 18 (+4) 10 (+0) 3 (-4) 10 (+0) 6 (-2)
  Skills Perception +2, Stealth +6
  Senses darkvision 60 ft., passive Perception 12
  Challenge 4 (1,100 XP)
  Blood Frenzy. The shark has advantage on melee
  attack rolls against any creature that doesn't have
  all its hit points.
  Swimby. The shark doesn't provoke an opportunity
  attack when it swims out of an enemy's reach.
  Water Breathing. The shark can breathe only
  underwater.
  Actions
  Bite. Melee Weapon Attack: +6 to hit, reach 5 ft.,
  one target. Hit: 10 (2d6 + 3) piercing damage.
  When the shark roll a 20 on this attack roll, roll
  another d20. If the shark rolls another 20, it bites
  off one of the target’s fingers or toes, with the
  effect of such loss determined by the DM. If the
  creature has no fingers or toes to sever, the shark
  bites off a portion of its body instead.
  Alister Konezegel's Field Guide Vol. II
  
  Giant Fisher Spider
  These unnaturally large spiders can be easily identified from
  other species of giant spider by their long legs and the
  hydrophobic hairs distributed across their bodies. These
  hairs repel water and allow the giant fisher spider to race
  across the surface of water, making them adept hunters in
  aquatic environments. Giant fisher spiders are capable of
  consuming prey as large as small sharks.
  Devoted Mothers. The females of this species carry their
  brood on their backs. The offspring of the giant fisher spider
  crawl across their bloated bodies, during which time the
  mother takes additional defensive precautions in order to
  protect her young.
  Dinner Date. This species of spider engages in a behavior
  commonly referred to as sexual cannibalism, whereby the
  females consumes the male following copulation (1).
  However, if the female witnesses her male counterpart fall in
  combat, she will race to his side and consume him.
  Sometimes this will grant the female just enough additional
  nutrients to magically give birth to a fresh brood of spiders.
  Unholy Origins. It is believed that this species arose from
  a fearsome battle between a regiment of exiled drow elves
  and a bloodthirsty troop of Demogorgon-worshippers. The
  only survivor of the drow regiment was a drider who pledged
  her allegiance to the Demogorgon, who blessed her with a
  brood of fearsome giant fisher spiders. Since then, giant
  fisher spiders have been found in the service of sahuagin
  tribes, though an unlucky traveler may also encounter them
  on rocky coastlines.
  5
  Giant Fisher Spider
  Large monstrosity, unaligned
  Armor Class 13 (15 with Spider Mother)
  Hit Points 93 (16d8+16)
  Speed 40 ft., climb 40 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  13 (+1)
  16 (+3)
  12 (+1)
  3 (-4)
  10 (+0)
  4 (-3)
  Skills Stealth +7
  Senses blindsight 10 ft., darkvision 60 ft., passive
  Perception 10
  Challenge 2 (450 XP)
  Spider Climb. The spider can climb difficult surfaces,
  including upside down on ceilings, without needing to
  make an ability check.
  Spider Mother. While a swarm of spiders occupies the
  same space as the spider, its AC increases by 2.
  Water Walker. The spider can walk across water.
  Web Sense. While in contact with a web, the spider
  knows the exact location of any other creature in
  contact with the same web.
  Web Walker. The spider ignores movement restrictions
  caused by webbing.
  Actions
  Bite. Melee Weapon Attack: +5 to hit, reach 5 ft., one
  creature. Hit: 7 (1d8 + 3) piercing damage, and the
  target must make a DC 11 Constitution saving throw,
  taking 9 (2d8) poison damage on a failed save, or half
  as much damage on a successful one. If the poison
  damage reduces the target to 0 hit points, the target is
  stable but poisoned for 1 hour, even after regaining hit
  points, and is paralyzed while poisoned in this way.
  Web (Recharge 5-6). Ranged Weapon Attack: Ranged
  Weapon Attack: +5 to hit, range 30/60 ft., one
  creature. Hit: The target is restrained by webbing. As an
  action, the restrained target can make a DC 12
  Strength check, bursting the webbing on a success.
  The webbing can also be attacked and destroyed (AC
  10; hp 5; vulnerability to fire damage; immunity to
  bludgeoning, poison, and psychic damage).
  Reactions
  Sexual Cannibalism (1/Day). When another spider that
  the giant fisher spider can see within 30 feet of it
  drops to 0 hit points, the giant fisher spider moves to
  it and rapidly consumes it, granting it the nutrition to
  summon a swarm of spiders. The swarm appears in an
  unoccupied space within 5 feet of the summoner and
  act as an ally of the summoner.
  Alister Konezegel's Field Guide Vol. II
  
  Giant Nudibranch
  Nudibranchs are sea slugs who are easily identified by their
  beautiful coloration and long fleshy appendages (papillae).
  They glide through coral reefs and along the sandy bottom of
  the sea searching for anenomes, barnacles, and sea sponges
  to consume. The giant variant of these creatures can grow up
  to 5 feet long.
  Defense Secretions. Nudibranchs possess several
  adaptations which help them to avoid predators and
  attackers, many of which take the form of acidic secretions
  that painfully deter those who would cause them harm (9).
  This acid can be harvested from the corpse of a giant
  nudibranch, but rogues beware: their slippery, mucous-
  covered bodies makes extracting this acid a particularly
  difficult affair.
  Kelp Blight
  While their land-bound cousins are created by the evil will of
  a Gulthias tree, kelp blights are granted life by a Gulthias
  anenome or a corrupted kelp forest. These creatures, when
  moving, resemble humanoids but are created entirely by
  twisting and writhing strands of giant kelp which teem with
  poison to deter herbivores (8).
  Light-Drinkers. Despite the circumstances of their birth,
  kelp blights retain certain qualities of the plant from which
  they are born. When struck with burning radiance, they are
  able to transform that light into energy and restore their
  wounds.
  6
  Giant Nudibranch
  Medium beast, unaligned
  Armor Class 14
  Hit Points 127 (23d8 + 23)
  Speed swim 30 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  10 (+0) 18 (+4) 13 (+1) 2 (-4) 10 (+0) 3 (-4)
  Damage Resistances acid
  Senses blindsight 10 ft., passive perception 10
  Challenge 4 (1,100 XP)
  Acid Splash. When the giant nudibranch takes
  damage of any type but psychic, each creature
  within 5 feet of the giant nudibranch takes 9 (2d8)
  acid damage.
  Slippery. The giant nudibranch has advantage on
  ability checks and saving throws made to escape a
  grapple.
  Water Breathing. The giant nudibranch can breathe
  only underwater.
  Actions
  Papillae Melee Weapon Attack: +6 to hit, reach 5 ft.,
  one target. Hit: 13 (3d8) acid damage.
  Kelp Blight
  Medium plant, neutral evil
  Armor Class 13 (natural armor)
  Hit Points 88 (16d8 + 16)
  Speed 30 ft., swim 30 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  13 (+1) 13 (+1) 12 (+1) 5 (-3) 10 (+0) 4 (-3)
  Condition Immunities blinded, deafened
  Senses blindsight 60 ft.
  Languages understands Common but can't speak
  Challenge 3 (700 XP)
  False Appearance. While the blight remains
  motionless, it is indistinguishable from giant kelp.
  Photosynthetic. Whenever the kelp blight is
  subjected to radiant damage, it takes no damage
  and regains a number of hit points equal to the
  radiant damage dealt.
  Actions
  Claws. Melee Weapon Attack: +3 to hit, reach 5 ft.,
  one target. Hit: 8 (2d6 + 1) slashing damage, and
  the target must succeed on a DC 13 Constitution
  saving throw or take 10 (3d6) poison damage. If
  the poison damage reduces the target to 0 hit
  points, the target is stable but poisoned for 1 hour,
  even after regaining hit points.
  Alister Konezegel's Field Guide Vol. II
  
  Merfolk Prismbringer
  In the deepest, darkest ocean, merfolk are locked in constant
  battle with sahuagin & other dark denizens of the sea. These
  merfolk eke out a harsh existence and struggle to maintain
  enough light to fend off their constant attackers. But once
  every thousand years, a special merfolk is born. Instead of
  the fish tail and scales of their fellows, these merfolk are born
  with rubbery purple skin, a shock of white hair, and a fan of
  cephalopod-like tentacles. The most immediately
  recognizable trait of these special merfolk, called the
  prismbringers, are the bright light that they emit from their
  bodies, bringing hope and radiance to their dark homes.
  Across the Spectrum. Merfolk prismbringers often
  become powerful arcane casters, channeling their biological
  ability to produce light (2) into magic that manipulates and
  refracts white light into colors from the entire visible
  spectrum. Merfolk prismbringers often learn to channel light
  and electricity to powerful effect, especially against
  waterbound foes.
  7
  Merfolk Prismbringer
  Medium humanoid (merfolk), neutral
  Armor Class 12
  Hit Points 150 (20d8 + 60)
  Speed 10 ft., swim 40 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  9 (-1) 18 (+4) 15 (+2) 16 (+3) 20 (+5) 12 (+1)
  Saving Throws Con +6, Wis +9, Cha +5
  Skills Arcana +7, History +7, Perception +9,
  Persuasion +5, Survival +9
  Senses darkvision 120 ft., truesight 30 ft., passive
  Perception 19
  Languages Aquan, Common
  Challenge 9 (5,000 XP)
  Amphibious. The merfolk can breathe air and water.
  Illumination. The merfolk sheds bright light in a 30-
  foot radius and dim light in an additional 30 ft.
  Innate Spellcasting. The merfolk's innate spellcasting
  ability is Wisdom (spell save DC 17). The merfolk
  can innately cast the following spells, requiring no
  components:
  At will: dancing lights, light, lightning lure
  3/day: shatter, lightning bolt
  2/day: cone of cold, wall of light
  1/day: chain lightning, prismatic spray
  Actions
  Tentacles. Melee Weapon Attack: +7 to hit, reach
  10 ft., one target. Hit: 11 (2d6 + 4) bludgeoning
  damage. If the target is a creature, it is grappled
  (escape DC 12). Until this grapple ends, the target
  is restrained, and the merfolk can't use their
  tentacles on another target.
  Alister Konezegel's Field Guide Vol. II
  
  Moray Dragon
  The moray dragon is a fearsome beast with a sinuous and
  scaly body that propels itself through the water with large,
  powerful fins. Its eyes and scales are often bright and vibrant
  colors which help it blend into the coral reefs it calls home.
  These dragons possess a second set of jaws within their
  throat which aid the creature in swallowing large prey (4).
  Reef Lairs. These evil creatures seek out and dig burrows
  into coral reefs. The water-bound dragons are known for
  attacking aquatic vessels and dashing them on reefs. Once
  they have sunk a ship, a moray dragon will hunt down and
  consume survivors. Then the monster will spend several days
  carefully foraging through the shipwreck for treasure, which
  they will then transport to their lair. Some moray dragons are
  said to have accumulated a great deal of wealth and
  treasure... An ample reward for heroes brave enough to face
  such a beast.
  8
  Moray Dragon
  Large dragon, chaotic evil
  Armor Class 16 (natural armor)
  Hit Points 152 (16d10 + 64)
  Speed 30 ft., burrow 20 ft., swim 30 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  18 (+4) 10 (+0) 18 (+4) 8 (-1) 11 (+0)
  14 (+2)
  Saving Throws Dex +3, Con +7, Wis +3
  Skills Perception +6, Stealth +3
  Senses blindsight 10 ft., darkvision 120 ft., passive
  Perception 16
  Languages Common, Draconic
  Challenge 8 (3,900 XP)
  Aggressive. As a bonus action, the moray dragon can
  move up to its speed toward a hostile creature it can
  see.
  Amphibious. The moray dragon can breathe air and
  water.
  Actions
  Multiattack. The dragon can use its Frightful Presence.
  It then makes two attacks: one with its bite and two
  with its fins.
  Frightful Presence. Each creature of the dragon's choice
  that is within 30 feet of the dragon and aware of it
  must succeed on a DC 14 Wisdom saving throw or
  become frightened for 1 minute. A creature can repeat
  the saving throw at the end of each of its turns, ending
  the effect on itself on a success. If a creature's saving
  throw is successful or the effect ends for it, the
  creature is immune to the dragon's frightful presence
  for the next 24 hours.
  Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one
  target. Hit: 20 (3d10 + 4) piercing damage, and the
  target is grappled (escape DC 11). Until this grapple
  ends, the target is restrained, and the dragon can't bite
  another target.
  Fins. Melee Weapon Attack: +7 to hit, reach 5 ft., one
  target. Hit: 11 (2d6 + 4) slashing damage.
  Pharyngeal Jaw. The dragon makes one bite attack
  against a Medium or smaller target it is grappling. If the
  attack hits, the target is swallowed, and the grapple
  ends. The swallowed target is blinded and restrained, it
  has total cover against attacks and other effects
  outside the dragon, and it takes 21 (6d6) acid damage
  at the start of each of the dragon's turns. The dragon
  can have only one target swallowed at a time. If the
  dragon takes 30 damage or more on a single turn from
  a creature inside it, the dragon must succeed on a DC
  20 Constitution saving throw at the end of that turn or
  regurgitate the swallowed creature, which falls prone in
  a space within 10 feet of the dragon. If the dragon dies,
  a swallowed creature is no longer restrained by it and
  can escape from the corpse using 5 ft. of movement,
  exiting prone.
  Alister Konezegel's Field Guide Vol. II
  
  Rahab
  The rahab is a demon with a humanoid upper body attached
  to a thick, slimy, and muscular lower body like that of a
  hagfish. The upper body of the creature bears spiny, powerful
  arms tipped with vicious claws and an unnaturally large head.
  The visage of a rahab features two large and unseeing eyes as
  well as a tentacled mouth bearing a long, toothed tongue that
  possesses the dexterity of a tentacle. These fiendish
  creatures hail from the briny waters of the 88th level of the
  Abyss and are considered powerful servants of the
  Demogorgon.
  Mucousal Masters. These demons are particularly
  nefarious due to their ability to generate a thick acidic slime
  that coats their body, which makes it difficult to pin a rahab
  down during a fight. In fact, when the rahab is attacked by a
  melee combatant, it is capable of immersing its attacker in
  slime, not only knocking them out of the fight but also leaving
  their quarry suffocating beneath the disgusting coating of
  ooze (10).
  9
  Rahab
  Large fiend (demon), chaotic evil
  Armor Class 18 (natural armor)
  Hit Points 255 (34d10+68)
  Speed 30 ft., burrow 20 ft., swim 60 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  16 (+3) 13 (+2) 14 (+2) 14 (+2) 12 (+1) 8 (-1)
  Saving Throws Dex +7, Wis +6
  Skills Stealth +7, Survival +6, Perception +6
  Damage Resistances cold, fire, lightning, poison;
  bludgeoning, piercing, and slashing From
  nonmagical attacks
  Damage Immunities acid
  Condition Immunities poisoned
  Senses blindsight 120 ft., passive Perception 14
  Languages Abyssal, Common, Sahuagin, telepathy 60 ft.
  Challenge 15 (13,000 XP)
  Amphibious. The rahab can breathe air and water
  Blood Frenzy. The rahab has advantage on melee attack
  rolls against any creature that doesn't have all its hit
  points.
  Magic Resistance. The rahab has advantage on saving
  throws against spells and other magical effects.
  Slippery. The rahab has advantage on ability checks and
  saving throws made to escape a grapple.
  Slime Discharge (3/day). When a creature touches the
  rahab or hits it with a melee attack while within 5 feet
  of it, the rahab may use its reaction to cover them with
  a suffocating slime. The target must succeed on a DC
  18 Dexterity saving throw or become engulfed by the
  slime. While engulfed, the target is restrained and
  unable to breathe, and takes 14 (4d6) acid damage at
  the start of each of its turns. A creature, including the
  target, can take its action to pull the target free by
  succeeding on a DC 18 Strength check.
  Actions
  Multiattack. The rahab makes four attacks: two claw
  attacks, one constrict attack, and one toothed tongue
  attack.
  Claw. Melee Weapon Attack: +8 to hit, reach 5 ft., one
  creature. Hit: 10 (2d6 + 3) slashing damage.
  Constrict. Melee Weapon Attack: +8 to hit, reach 5 ft.,
  one creature. Hit: 13 (3d6 + 3) bludgeoning damage
  plus 7 (2d6) acid damage, and the target is grappled
  (escape DC 18). Until this grapple ends, the creature is
  restrained and takes 13 (3d6 + 3) bludgeoning damage
  plus 7 (2d6) acid damage at the start of each of its
  turns, and the rahab can't constrict another target.
  Toothed Tongue. Ranged Weapon Attack: +7 to hit,
  range 10/35 ft., one target. Hit: 9 (2d6 + 3) piercing
  damage.
  Alister Konezegel's Field Guide Vol. II
  
  Scorpionfish Devil
  These infernal creatures have the appearance of an
  emaciated, quadrapedal creatures with gray flesh and spine-
  encrusted skin (as depicted on page 2). Their sallow eyes
  glow with sulfurous light and they are known as some of the
  most dangerous inhabitants of the River Styx in the Nine
  Hells.
  Infernal Poison. Scorpionfish devils possess a deadly
  toxin within their blood that they are able to inject into others
  via their vicious bite and their insidious spines. Once within
  the victim's bloodstream, this venom causes incredible pain
  and immediate swelling and inflammation of the affected
  area (5). This swelling is known to make even the simplest of
  movements more difficult and can bring even the most
  dextrious individuals to their knees.
  Winter Toad
  The winter toad has skin with the color and texture of freshly
  fallen snow, allowing it to hide well during the snowy months.
  Frozen. The winter toad has taken the natural ability of
  amphibians to survive through cold winters (3) to terrifying
  heights. These toads can freeze their prey into solid ice.
  Signs in arctic regions often warn travelers of winter toads.
  10
  Scorpionfish Devil
  Medium fiend (devil), unaligned
  Armor Class 16 (natural armor)
  Hit Points 110 (30d8 + 28)
  Speed 20 ft., swim 40 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  16 (+3) 17 (+3) 14 (+2) 11 (+0) 13 (+1) 16 (+3)
  Skills Perception +5, Stealth +7
  Damage Resistances fire, poison; bludgeoning, piercing,
  and slashing from nonmagical weapons that aren't
  silvered
  Damage Immunities cold
  Condition Immunities poisoned
  Senses blindsight 15 ft., darkvision 60 ft., passive
  Perception 15
  Languages Infernal, telepathy 30 ft.
  Challenge 10 (5,900 XP)
  Devil's Sight. Magical darkness doesn't impede the
  devil's darkvision.
  Limited Spines. The devil has twelve dorsal spines. Used
  spines regrow by the time the devil finishes a long rest.
  Magic Resistance. The devil has advantage on saving
  throws against spells and other magical effects.
  Actions
  Multiattack. The devil makes three attacks: one with its
  bite and two with its claws or three with its dorsal
  spine.
  Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one
  target. Hit: 14 (2d10 + 3) piercing damage, and the
  target must succeed on a DC 16 Constitution saving
  throw or take 21 (6d6) poison damage and become
  posioned, or half damage on a successful save. While
  poisoned this way, a creature has disadvantage on
  Dexterity checks and saving throws.
  Claws. Melee Weapon Attack: +7 to hit, reach 5 ft., one
  target. Hit: 12 (2d8 + 3) slashing damage.
  Dorsal Spine. Ranged Weapon Attack: +7 to hit, range
  20/80 ft ., one target. Hit: 10 (3d4 + 3) piercing
  damage plus 10 (3d6) poison damage.
  Winter Toad
  Medium monstrosity, unaligned
  Armor Class 13
  Hit Points 78 (17d8)
  Speed 30 ft., swim 30 ft.
  STR
  DEX
  CON
  INT
  WIS
  CHA
  12 (+1)
  13 (+2)
  11 (+0)
  4 (-3)
  11 (+0)
  5 (-3)
  Skills Stealth +4, Perception +2
  Damage Immunities cold
  Condition Immunities petrified
  Senses tremorsense 30 ft., passive perception 10
  Challenge 3 (700 XP)
  Snow Camouflage. The toad has advantage on Dexterity
  (Stealth) checks made to hide in snowy terrain.
  Actions
  Bite. Melee Weapon Attack: +3 to hit, reach 5 ft., one
  target. Hit: 8 (2d6 + 1) piercing damage. The target is
  grappled (escape DC 11) Until this grapple ends, the
  target is restrained, and the toad can't bite another
  target.
  Frostbite (Recharge 5-6). The toad makes one bite
  attack against a Medium or smaller target it is
  grappling. If the attack hits, the target takes an
  additional 10 (3d6) cold damage and is injected with
  freezing toxins, and the grapple ends. The target must
  make a DC 12 Constitution saving throw. On a failed
  save, the creature magically begins to turn to ice and is
  restrained. It must repeat the saving throw at the end
  of its next turn. On a success, the effect ends. On a
  failure, the creature is petrified until freed by the
  greater restoration spell or other magic.
  Alister Konezegel's Field Guide Vol. II
  
  Acknowledgements
  I'd first like to thank my gaming group for tolerating the
  bizarre, science-inspired monsters I've thrown at them for
  almost two years. Aelin, Madrigal, Rhino, & Teia, thank you
  for being my willing guinea pigs!
  And another huge thanks to those artists whose work has
  been used in this bestiary! 
  Cover Art, Page 2, 3, 4, 5, 6, 6, 7, 8, 9, 11 - DMsGuild Creator
  Resources
  Works Cited
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  Cannibalism in the Semi-Aquatic Fishing Spider,
  Dolomedes fimbriatus (Clerck) (Araneae: Pisauridae). The
  Journal of Arachnology, 20(3), 222–226. Retrieved from
  JSTOR.
  Hastings, J. W. (1996). Chemistries and colors of
  bioluminescent reactions: A review. Gene, 173(1), 5–11.
  https://doi.org/10.1016/0378-1119(95)00676-1
  Larson, D. J., Middle, L., Vu, H., Zhang, W., Serianni, A. S.,
  Duman, J., & Barnes, B. M. (2014). Wood frog adaptations
  to overwintering in Alaska: New limits to freezing
  tolerance. Journal of Experimental Biology, 217(12),
  2193–2200. https://doi.org/10.1242/jeb.101931
  Mehta, R. S., & Wainwright, P. C. (2007). Raptorial jaws in
  the throat help moray eels swallow large prey. Nature,
  449(7158), 79–82. https://doi.org/10.1038/nature06062
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  E. L., Lemos, E. M., Bissoli, N. S., … Figueiredo, S. G.
  (2012). Local inflammatory response induced by
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  Goodmanlowe, G. D., & Lowe, C. G. (2010). Foraging
  ecology of Cookiecutter Sharks (Isistius brasiliensis) on
  pelagic fishes in Hawaii, inferred from prey bite wounds.
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  Pietsch, T. W. (2005). Dimorphism, parasitism, and sex
  revisited: Modes of reproduction among deep-sea
  ceratioid anglerfishes (Teleostei: Lophiiformes).
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  Steinberg, P. D. (1984). Algal Chemical Defense Against
  Herbivores: Allocation of Phenolic Compounds in the Kelp
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  opisthobranchs. Journal of the Marine Biological
  Association of the United Kingdom, 39(1), 123–134.
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  Zintzen, V., Roberts, C. D., Anderson, M. J., Stewart, A. L.,
  Struthers, C. D., & Harvey, E. S. (2011). Hagfish predatory
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  Looking for Liches?
  Are you curious about the Green Hand, a mysterious trio of
  liches who created and employ some of these aquatic terrors?
  Do you wish to seek the mindflayer lich who within the
  flooded Eternal Spirals? If you seek this information or more,
  keep an eye out for Pretty Little Liches, coming out on the
  DMs Guild in Fall 2019.
  Pretty Little Liches contains the background information
  and stat blocks for three unique liches as well as maps of
  their respective lairs. Each lair will include traps, puzzles,
  monsters, treasure, and NPCs appropriate for Tier 3 & 4
  characters in 5th Edition Dungeons & Dragons!
  Monsters by CR
  CR 2
  Giant Fishing Spider 
  CR 3
  Kelp Blight 
  Winter Toad
  CR 4
  Cookiecutter Shark 
  Giant Nudibranch
  CR 5
  Arcanelure Anglerfish 
  CR 8
  Moray Dragon 
  CR 9
  Merfolk Prismbringer 
  CR 10
  Scorpionfish Devil 
  CR 15
  Rahab 
  11
  Alister Konezegel's Field Guide Vol. II
  
SOURCE: textdata/thevault/Dungeons & Dragons [multi]/Monster books/Alister Konezegel's Field Guide Volume 2 - Aquatic Terrors.pdf