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Ancient Sea Serpent

Gargantuan Dragon · Neutral · CR 14

  • Dragon
  • Gargantuan
  • Tier 3
  • Neutral

As a gargantuan dragon (neutral), Ancient Sea Serpent carries CR 14. Common in underwater environments. Sourced from Fizban's Treasury of Dragons.

Stat Block

Challenge Rating
14
Type
Dragon
Size
Gargantuan
Alignment
Neutral
Speed
20, swim 60
Habitats
Underwater
Sources
Fizban's Treasury of Dragons

Ecology

Ancient Sea Serpent is one of the elder species, claiming a wide territory and shaping the ecology around it for centuries. It is most often found in underwater regions. It is gargantuan-sized, which shapes how it hunts, hides, or fights. As a legendary creature, it is rare in the world and likely the only specimen of its kind in the local region.

Behaviour

Ancient Sea Serpent is intelligent, vain, long-memoried; it remembers slights for centuries and rewards loyalty in kind. Its Neutral alignment shapes how it engages with the world — predictable in tendency, even when unpredictable in detail. It is intelligent enough to plan, scheme, or remember.

Origin

Ancient Sea Serpent is expanded in Fizban's Treasury of Dragons. Dragons in D&D canon trace to Bahamut and Tiamat, with each lineage having its own founding myth. Within a campaign, its existence anchors a region with the kind of weight only an old, named species carries.

CR 14 monstersAll DragonsUnderwater

Related Monsters

Frequently Asked Questions about Ancient Sea Serpent

What is the challenge rating of Ancient Sea Serpent?
On the bestiary CR scale, Ancient Sea Serpent sits at 14. It matches tier-3 encounter math.
What type of creature is Ancient Sea Serpent?
By creature type, Ancient Sea Serpent is a dragon, gargantuan size, neutral alignment.
Where does Ancient Sea Serpent live?
The bestiary places Ancient Sea Serpent in Underwater.
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QR code linking to Ancient Sea Serpent — https://www.doungim.com/dnd/monsters/ancient-sea-serpent Scannable QR code encoding the URL https://www.doungim.com/dnd/monsters/ancient-sea-serpent. Point a phone camera at this code to open the Ancient Sea Serpent page on your mobile device — useful at the table when a DM's laptop or a printed sheet is showing the page.
Scannable QR code encoding the URL https://www.doungim.com/dnd/monsters/ancient-sea-serpent. Point a phone camera at this code to open the Ancient Sea Serpent page on your mobile device — useful at the table when a DM's laptop or a printed sheet is showing the page.