Coastline Reaper

Large monstrosity, unaligned

Armor Class 16 (natural armor)
Hit Points 144 (17d10 + 51)
Speed 10 ft., swim 40 ft.

10 (+0) 18 (+4) 17 (+3) 4 (–3) 14 (+2) 8 (–1)

Saving Throws Con +7, Dex +8
Skills Athletics +4, Stealth +8, Survival +6
Damage Resistances cold, poison
Condition Immunities exhaustion, poisoned
Senses darkvision 60 ft., passive Perception 12
Challenge 9 (5,000 XP)
Proficiency Bonus +4


  • Glowing Organs. While underwater, the coastline reaper’s internal organs glow an eerie, pale blue, shedding dim light in a 10-foot radius.
  • Hold Breath. While out of water, the coastline reaper can hold its breath for 30 minutes.
  • Water Breathing. The coastline reaper can breathe only underwater.


  • Multiattack. The coastline reaper makes two Tentacle Lash attacks and one Stinging Tentacle attack.
  • Tentacle Lash. Melee Weapon Attack: +8 to hit, reach 15 ft., one target. Hit: 14 (3d6 + 4) bludgeoning damage.
  • Stinging Tentacle. Melee Weapon Attack: +8 to hit, reach 15 ft., one target. Hit: 7 (1d6 + 4) piercing damage plus 9 (2d8) poison damage. The target must succeed on a DC 16 Constitution saving throw or be paralyzed for 1 minute. A frightened creature has disadvantage on this saving throw. The paralyzed target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
  • Frightening Visage (Recharge 5–6). If underwater, the coastline reaper flares the light from its organs, making the skull-like structure within more apparent. If above water, the coastline reaper tightly pulls in its outer flesh, causing its body to take on a fleshy, skull-like appearance. Each Humanoid within 30 feet of the coastline reaper that can see it must make a DC 16 Wisdom saving throw. On a failure, a creature takes 21 (6d6) psychic damage and is frightened for 1 minute. On a success, a creature takes half the damage and isn’t frightened. A frightened creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.


Tentacles rise out of the water, whipping about as the creature pulls itself up from the depths. Its bulbous head resembles a jellyfish, but its flesh sinks into holes created by its internal organs, giving its body the appearance of a large skull crowned with rows of spikes.

Coastal Boogeyman. Communities that live near coasts tell stories of the coastline reaper to their children to keep them away from the beach at night. Coastline reapers live in submerged caves and hunt along coasts when the tide is high. Fisherfolk who know there is a lair nearby always go out onto the waters at low tide or in large groups to avoid encountering the coastline reaper. The reaper gets its name from the unique pattern that appears on its bulbous head. It can deflate the outer flesh of its head, which sinks into holes created by the arrangement of its internal organs. The end result resembles a humanoid skull crowned in spikes, provoking fear in those who see it. When the reaper is submerged, these organs glow a pale blue, evoking a ghostly skull-like appearance as the reaper swims.

Deadly Hunter. Coastline reapers hunt the coast for aquatic life to feed on, but those near settlements are fond of the taste of humanoids. Such reapers quickly learned their appearance frightens humanoids and have adapted their hunting techniques over time to capitalize on this fear.

Some of the reaper’s tentacles are covered in small stingers filled with a paralyzing poison that is particularly effective against frightened creatures.

Dark Allies and Rivals. Though not quite sentient, coastline reapers can learn basic words and signals, making them desirable minions for creatures such as aboleths. Coastline reapers dislike the unpalatable sahuagin, who often hunt in the reaper’s territory, and reapers go out of their way to destroy sahuagin colonies in their territory.

Section 15: Copyright Notice

Tome of Beasts 3 © 2022 Open Design LLC; Authors: Eytan Bernstein, Celeste Conowitch, Benjamin L. Eastman, Robert Fairbanks, Scott Gable, Basheer Ghouse, Richard Green, Jeremy Hochhalter, Jeff Lee, Christopher Lockey, Sarah Madsen, Ben Mcfarland, Jonathan Miley, Kelly Pawlik, Sebastian Rombach, Chelsea Steverson, Brian Suskind, Mike Welham

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