Birgemon Seal

Medium aberration, unaligned

Armor Class 12
Hit Points 60 (8d8 + 24)
Speed 20 ft., swim 60 ft.

12 (+1) 15 (+2) 16 (+3) 4 (–3) 12 (+1) 9 (–1)

Skills Perception +3, Stealth +4
Damage Resistances acid, cold
Senses darkvision 60 ft., passive Perception 13
Challenge 2 (450 XP)
Proficiency Bonus +2


  • Frozen to the Spot. When on snow or ice, the birgemon seal can’t be moved against its will.
  • Hold Breath. The birgemon seal can hold its breath for 90 minutes.


  • Multiattack. The birgemon seal makes one Bite attack, one Toothy Maw attack, and three Tendril attacks. It can replace all three Tendril attacks with a use of Reel.
  • Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 7 (2d4 + 2) piercing damage.
  • Toothy Maw. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 9 (2d6 + 2) piercing damage.
  • Tendril. Melee Weapon Attack: +4 to hit, reach 15 ft., one target. Hit: The target is grappled (escape DC 13) if it is a Medium or smaller creature, and the seal can’t use the same tendril on another target. If a creature is grappled by two or more tendrils, it is also Restrained.
  • Reel. The birgemon seal pulls each creature grappled by it up to 10 feet straight toward it.


  • Ice Slide. If the birgemon seal moves at least 10 feet in a straight line while on snow or ice during its turn, it can slide up to 40 feet.


Only a moment before it was a seal with large, glossy eyes. Then its strange bony growths split, revealing a massive, toothy maw. Three tentacles reach out from within. The birgemon seal is infected with an extraplanar parasite. Sages who have studied birgemon seals discovered the parasites prefer the cold of the arctic and infect only seals.

Inherited Parasite. The parasite influences the behavior of the seal, but the infected seal population acts normally, even following the same migratory patterns. Birgemon seals pass along the parasite to their young during birth, leaving whole generations of seals that know no other existence. Though infected seals act as any other seal, seal that aren’t infected tend to stay away from those that are. Shimmer seals kill birgemon seals on sight and have been observed leading uninfected seals in fights against pods of birgemon seals.

Symbiotic Existence. The parasite alters its host by forming a toothy, tentacled maw on the seal’s back, but it otherwise doesn’t harm, hinder, or alter the seal. Birgemon seals are content to eat with either mouth, though some prey is far easier for the aberrant maw to hunt and devour. These seals also survive predation more than those that aren’t infected, but birgemon seals killed and eaten don’t infect the predator with the parasite, which dies alongside its host.

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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