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Sea Serpent, Brine

Family: Sea Serpents

Huge dragon, chaotic evil

Armor Class 18 (natural armor)
Hit Points 195 (17d12 + 85)
Speed 0 ft., swim 60 ft.

21 (+5) 15 (+2) 20 (+10) 7 (-2) 13 (+1) 14 (+2)

Saving Throws Strength +10, Dexterity +7, Constitution +9
Skills Athletics +10, Perception +6
Damage Immunities acid
Condition Immunities prone
Senses darkvision 60 ft., passive Perception 16
Languages Aquan, Draconic
Challenge 13 (10,000 XP)

Special Traits

  • Amphibious. The brine sea serpent can breathe air and water.


  • Multiattack. A brine sea serpent attacks once with its bite and once with its tail.
  • Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 21 (3d10 + 5) piercing damage plus 10 (3d6) acid damage, and the target is grappled (escape DC 18). If the brine sea serpent already has a creature grappled with its bite, it can only bite that creature, and it has advantage on that attack.
  • Tail Slap. Melee Weapon Attack: +10 to hit, reach 15 ft., one target. Hit: 18 (3d8 + 5) bludgeoning damage and the target must succeed at a DC 18 Strength saving throw or be pushed 10 feet away and knocked prone.
  • Brine Blast (Recharge 6). The brine serpent releases a 50-foot cone of briny acid. Creatures in the area must make a DC 18 Dexterity saving throw. On a failed saving throw, the target takes 72 (16d8) acid damage.

Legendary Actions

The brine sea serpent can take up to 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature’s turn. The serpent regains spent legendary actions at the start of its turn.

  • Tail Attack. The brine serpent uses its tail attack.
  • Coiling Maneuver (Costs 2 Actions). The brine sea serpent attempts to grapple a Large or smaller target. The target must make a DC 18 Strength saving throw or be grappled and restrained. The sea serpent can’t use its other legendary actions or its Tail Slap if it’s grappling a target. At the beginning of each of the brine serpent’s turns, the grappled target takes 18 (3d8 + 5) bludgeoning damage.


Nearly as old as the dragons that roam the sky, sea serpents are great snakelike creatures that have roamed the oceans for ages. Unlike the classical dragon, these great, scaly, serpentine beasts are generally agreed to be a product of evolution though many suspect magical influence, either deliberate or natural, somewhere in their evolution.

Whatever their origins, sea serpents are a highly-varied species, with great variation in size, coloration, intellect, and temperament. However, all sea serpents bear certain similarities. They are long, sinuous, warm-blooded creatures that closely resemble snakes in appearance, though they all have two sets of flippers, which may be large or so small and atrophied as to be nearly unnoticeable. Sea serpents are aquatic creatures, though some can make their way about on land. All sea serpents can breathe both water and air with equal efficiency, another fact that distinguishes them from marine mammals and reptiles. Further, all sea serpents are sentient, with an intellect ranging from little greater than moronic to supragenius level.

One trait that sea serpents share in common with their draconic brethren is a sense of innate superiority, a feeling that they are masters of the sea, at least in whatever manner they choose to pursue their expertise.

Unlike dragons, however, sea serpents are not distinguished by color or age category. And while some species are as acquisitive as dragons, others have no interest in hoarding wealth and live lives little better than beasts.

All sea serpents can speak and understand Aquatic, and many know Draconic as well. The more intelligent species may also learn the languages of marine civilizations or the languages of sea-traveling surface-dwellers.

Due to their physical similarities, sea serpents use fairly consistent tactics in combat situations. All sea serpents have venomous bites, and they use this to their advantage to slow or immobilize multiple attackers so they can concentrate on one foe. In addition to their lethal bite, all sea serpents have the ability to ensnare prey in their coils as a giant constrictor does and crush the life out of them. The larger sea serpents may even use this constriction attack against sea vessels, and mariners in their smoky dens delight in recounting tales of horror and woe of great serpents that splinter hulls and then devour the helpless sailors in the water.

Because they are sentient beings, sea serpents can often be reasoned with even if the reasoning is no more complex than simple intimidation. They are adaptable to circumstances, and none throw themselves into battle rashly. This serpentine creature is about 20 feet long, nose to tail, with two sets of large flippers and a wide body. A finned crest runs the length of its back, head to tail. The body is dark blue with a lighter underbelly, often tinged with rust or green highlights. The brine sea serpent is a relatively stupid and aggressive predator of the deeps and is the only sea serpent with a breath weapon. The brine sea serpent lives in caves in the ocean floor, where it maintains a hoard much like a dragon. It often lives in seas known for their stormy conditions, since it enjoys feeding on humans capsized from boats. Sometimes it even attacks ships directly if it is hungry. It also searches sunken ships for objects of interest to add to its hoard. The eyes of a brine serpent are small, but it possesses large ears and has exceptional hearing.

Against lone prey, the brine sea serpent likely closes and attack with its bite.

When confronting larger groups, it uses its breath weapon first – the brine sea serpent has a special organ that harvests sodium from seawater and stores it in concentrated form in a gland in its cheek. It generally avoids constricting attacks unless attacking large opponents that do not die from its poisonous bite. The brine sea serpent may also use the constriction attack against small sea vessels if it is very hungry.

Section 15: Copyright Notice

Tome of Horrors © 2018, Frog God Games, LLC; Authors: Kevin Baase, Erica Balsley, John “Pexx” Barnhouse, Christopher Bishop, Casey Christofferson, Jim Collura, Andrea Costantini, Jayson ‘Rocky’ Gardner, Zach Glazar, Meghan Greene, Scott Greene, Lance Hawvermale, Travis Hawvermale, Ian S. Johnston, Bill Kenower, Patrick Lawinger, Rhiannon Louve, Ian McGarty, Edwin Nagy, James Patterson, Nathan Paul, Patrick N. Pilgrim, Clark Peterson, Anthony Pryor, Greg Ragland, Robert Schwalb, G. Scott Swift, Greg A. Vaughan, and Bill Webb