Dragon, Oillipheist

Family: Dragons

Huge dragon, unaligned

Armor Class 15 (natural armor)
Hit Points 136 (13d12 + 52)
Speed 20 ft., swim 50 ft.

23 (+6) 14 (+2) 18 (+4) 2 (-4) 13 (+1) 9 (-1)

Skills Perception +4, Stealth +5
Senses darkvision 60 ft., passive Perception 14
Proficiency Bonus +3
Challenge 8 (3,900 XP)


  • Hold Breath. The oillipheist can hold its breath for up to 1 hour.
  • Keen Senses. The oillipheist has advantage on Wisdom (Perception) checks that rely on hearing or smell.
  • Invisible in Water. The oillipheist is invisible while fully immersed in water.


  • Multiattack. The oillipheist makes two attacks: one with its Bite and one with its Tail Slap.
  • Bite. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 28 (4d10 + 6) piercing damage and the target is swallowed if it is a Large or smaller creature. The swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the oillipheist, and it takes 16 (3d10) acid damage at the start of each of the oillipheist’s turns. The oillipheist can have only one creature swallowed at a time. If the oillipheist takes 30 damage or more on a single turn from a creature inside it, the oillipheist must succeed on a DC 15 Constitution saving throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10 feet of the oillipheist. If the oillipheist dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 15 feet of movement, exiting prone.
  • Tail Slap. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 20 (4d6 + 6) bludgeoning damage. If the target is a creature, it must succeed on a DC 17 Strength saving throw or be knocked prone.


The oillipheist has a serpentine body that resembles that of a whale, with a long neck that extends above the surface of the water. Its hide is dark in color, with shades of green and black that help it blend into the depths of the loch. The oillipheist can reach lengths of up to 30 feet, including a tail that is half as long as its body. When it moves, the water churns and foams around it, creating waves.

The oillipheist is a creature steeped in legend and folklore, with tales of its existence dating back for generations. It is a solitary creature that roams the depths of the loch, rarely venturing into the open sea. The oillipheist is a fierce predator, known to attack anything it notices, including boats and swimming individuals. Its aggressive nature and enormous size have made it the subject of fascination and fear among those who live near the loch.

The oillipheist primarily inhabits the deep waters of lochs, where it finds ample prey and can hide from prying eyes. It prefers areas with broken terrain and underwater caves, providing it with shelter and ambush points. The creature is highly adapted to aquatic life and can hold its breath for extended periods of time. While it spends most of its life in the water, the oillipheist still requires air and must surface periodically to breathe.

The oillipheist is an agile predator, using its size and maneuverability to its advantage. When hunting, it swims with its head above the water, scanning the surroundings for potential prey. It can quickly lunge forward, snapping its jaws shut on unsuspecting victims. The oillipheist’s bite is powerful enough to inflict significant damage, and it can also deliver crushing tail slaps to incapacitate or stun its prey. Once a target is captured, the oillipheist can swallow it whole, temporarily incapacitating the victim and allowing the oillipheist to consume its meal at its leisure.

Oillipheists that are truly ancient can grow to monstrous sizes in very large lochs. Those rare carers, known as caoranachs, are nigh unstoppable eating machines that can swallow entire herds of cattle whole.

Section 15: Copyright Notice

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

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