Huge monstrosity, unaligned

Armor class 16 (natural armor)
Hit points 169 (16d12 + 64)
Speed 20 ft., swim 60 ft.

20 (+5) 14 (+2) 18 (+4) 4 (-3) 10 (+0) 6 (-2)

Skills Perception +3, Stealth +5
Damage Vulnerabilities force
Senses darkvision 60 ft., passive Perception 13
Proficiency Bonus +3
Challenge 8 (3,900 XP)


  • Hold Breath. While out of water, the muirselche can hold its breath for 1 hour.
  • Underwater Camouflage. The muirselche has advantage on Dexterity (Stealth) checks made while underwater.
  • Water Breathing. The muirselche can breathe only underwater.


  • Multiattack. The muirselche makes three attacks: one with its Beak and two with its Tentacles.
  • Bite. Melee Weapon Attack: +8 to hit, reach 10 ft., one target. Hit: 16 (2d10 + 5) piercing damage and the target is swallowed if it is a Medium or smaller creature. A swallowed creature is blinded and restrained, has total cover against attacks and other effects outside the muirselche, and takes 10 (3d6) acid damage at the start of each of the muirselche’s turns. The muirselche’s gullet can hold up to two creatures at a time. If the muirselche takes 20 damage or more on a single turn from a creature inside it, the muirselche must succeed on a DC 15 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, each of which falls prone in a space within 10 feet of the muirselche. If the muirselche dies, any swallowed creature is no longer restrained by it and can escape from the corpse using 10 feet of movement, exiting prone.
  • Tentacle. Melee Weapon Attack: +8 to hit, reach 20 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage. If the target is a Medium or smaller creature, it must succeed on a DC 16 Strength saving throw or be grappled (escape DC 16). The muirselche can have up to eight creatures grappled at a time using its tentacles.
  • Ink Cloud (Recharges after a Short or Long Rest). A 20-foot-radius cloud of ink extends all around the muirselche if it is underwater. The area is heavily obscured for 1 minute, although a significant current can disperse the ink. After releasing the ink, the muirselche can use the Dash action as a bonus action.
  • Whirlpool (1/Day). The muirselche causes a whirlpool to form, centered on itself. The whirlpool forms a vortex that is 5 feet wide at the base, up to 50 feet wide at the top, 25 feet tall, and lasts for 1 minute or until the muirselche is incapacitated. Any creature or object in the water and within 25 feet of the vortex is pulled 10 feet toward it. A creature can swim away from the vortex by succeeding on a DC 16 Strength (Athletics) check. When a creature enters the vortex for the first time on a turn or starts its turn there, it must make a DC 16 Strength saving throw. On a failed save, the creature takes 9 (2d8) bludgeoning damage and is caught in the vortex until it ends. On a success, the creature takes half damage and isn’t caught in the vortex. A creature caught in the vortex can use its action to try to swim away from the vortex as described above, but it has disadvantage on the Strength (Athletics) check to do so. The first time each turn that an object enters the vortex, the object takes 9 (2d8) bludgeoning damage. This damage occurs each round it remains in the vortex. If the creature is pulled to the center, the muirselche can make a bite attack as a bonus action.


The muirselche is a huge aquatic creature that resembles an enormous octopus, with immense tentacles and a bulbous central body. Its pale skin is covered in suction cups, and its eyes are large and unblinking. At its center is a massive maw that resembles a gaping treasure bag, capable of sucking in both objects and unfortunate beings.

The muirselche is typically found in the depths of the ocean, lurking in underwater caverns and dark trenches. It’s a solitary creature, seldom encountered by surface-dwelling races. It often preys on other sea creatures and occasionally ventures to shallower waters in search of prey.

The muirselche is a cunning predator that uses its powerful tentacles to ensnare and immobilize its victims. It’s known for its ability to create an ink cloud, shrouding its surroundings in darkness and confusion, giving it an advantage in escaping from dangerous situations or surprising its prey. The muirselche’s most fearsome ability is its suction attack, which can pull in and grapple creatures as large as armored warriors.

In legends, the muirselche is often portrayed as a menacing force of the sea, capable of great destruction. The creature’s appetite for treasure and its ability to consume armored warriors whole has made it a symbol of greed and gluttony. In the tales, heroes or gods are needed to confront the muirselche, often utilizing powerful magic or divine weapons to defeat it.

Section 15: Copyright Notice

5E RPG: Celtic Bestiary. Copyright 2023, Mal and Tal Enterprises, LLC; Author Michael Tresca.

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