Dragon, Sea - Ancient

This aquamarine dragon has a shark’s head that tapers off into a sleek eel-like body. Its large fins double as wings.

Divine Dragons. Sea dragons are the children of the ocean, and believe they are semi-divine beings, worthy of worship. Given their size and power, they may be right; certainly, they are often companions or steeds to gods of the sea.

Despite the solemn duties the sea dragons invoke thanks to their lineage, they are extremely whimsical. While these immense creatures are playful, their games can shatter hulls and drown sailors. The sea dragons course through the waves with tangible joy as they hunt whales and entire schools of tuna.

Shipwreck Art. Sea dragons love collecting treasure, especially prize the sunken treasure-filled hulls of ships lost to storm, battle, or their own handiwork. While they appreciate all wealth, they prefer hardy items that can stand up to long exposure to sea water. Precious metals and gemstones add a dramatic luster to the dragon’s lair when they catch stray beams of light. Sea dragons take any more perishable treasures and place them on a reef-altar, to dissolve in the sea as a tithe to the sea gods.

Sunken Memorials. A sea dragon’s lair is littered with meticulously arranged ships consigned to the deeps. These wrecks are often artfully smashed to allow the treasures in the hold to spill out onto the sea floor. It may seem haphazard, but it displays a complex aesthetic that only other sea dragons can truly appreciate. Because they arrange these wrecks so carefully, a dragon notices immediately if its hoard is disturbed.

Sea Dragon’s Lair

Sea dragons dwell in lairs dwell in lairs beneath the waves: ocean fissures and caves, lightless trenches full of strange rock formations, and sheltered reefs of cultivated coral.

Whatever the place, it’s dedicated to the worship of sea gods. Despite the draconic instinct for seclusion and protection when choosing a lair, sea dragons always choose lairs relatively close to humanoid trade routes and abundant supplies of fish.

The sky surrounding a sea dragon’s lair is perpetually stormy, and the seas run high. If a captain is courageous, these high winds and swift-running currents can cut significant time off a voyage.

Lair Actions

On initiative count 20 (losing initiative ties), the dragon takes a lair action and generates one of the following effects. The dragon can’t use the same effect two rounds in a row:

  • Four vortexes, each 5 feet in diameter and up to 30 feet tall, appear within the lair where the dragon wishes. Creatures occupying the space where a vortex appears or who enter the vortex for the first time on a turn must make a DC 15 Dexterity save or be restrained. As an action, a creature can free itself or another creature from a vortex by succeeding on a DC 15 Strength check. The vortexes last until the dragon uses this lair action again or until the dragon dies.
  • The dragon creates a wall of living coral on a solid surface it can see within 120 feet of it. The wall can be up to 30 feet long, 30 feet high, and 1 foot thick. When the wall appears, each creature within its area takes damage as if touching the wall and is pushed 5 feet out of the wall’s space, on whichever side of the wall it wants. Touching the wall releases painful stings that deal 18 (4d8) poison damage, or half that with a successful DC 15 Constitution saving throw. Each 10-foot section of the wall has AC 5, 30 hit points, resistance to fire damage, and immunity to psychic damage. The wall lasts until the dragon uses this lair action again or until the dragon dies.
  • The dragon bends time around its enemies. Four creatures the dragon can see within 120 feet of it must succeed on a DC 15 Wisdom save or be affected by a slow spell. This effect last until initiative count 20 on the following round.

Regional Effects

The region containing a legendary sea dragon’s lair is warped by the dragon’s magic, which creates one or more of the following effects:

  • Sea life becomes richer within 6 miles of the lair. Schools of fish move into new waters, sharks become common, and whale migration paths shift to pass near the area.
  • Water temperatures drop sharply within 6 miles of the lair. Creatures not accustomed to cold suffer exposure to extreme cold while swimming in this water.
  • Storms and rough water are more common within 6 miles of the lair.

If the dragon dies, conditions of the sea surrounding the lair return to normal over the course of 1d10 days.

Ancient Sea Dragon

Gargantuan dragon, neutral evil
Armor Class 22 (natural armor)
Hit Points 481 (26d20 + 208)
Speed 40 ft., fly 80 ft., swim 80 ft.
29 (+9) 10 (+0) 27 (+8) 19 (+4) 17 (+3) 21 (+5)

Saving Throws Dex +7, Con +15, Wis +10, Cha +12
Skills Perception +17, Stealth +7
Damage Immunities cold
Senses blindsight 60 ft., darkvision 120 ft., passive Perception 27
Languages Common, Draconic, Infernal, Primordial
Challenge 22 (41,000 XP)

Amphibious. The dragon can breathe air and water.

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Siege Monster. The dragon deals double damage to objects and structures.


Multiattack. The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +16 to hit, reach 15 ft., one target. Hit: 20 (2d10 + 9) piercing damage plus 11 (2d10) cold damage.

Claw. Melee Weapon Attack: +16 to hit, reach 10 ft., one target. Hit: 16 (2d6 + 9) slashing damage.

Tail. Melee Weapon Attack: +16 to hit, reach 20 ft., one target. Hit: 18 (2d8 + 9) bludgeoning damage.

Frightful Presence. Each creature of the dragon’s choice that is within 120 feet of the dragon and aware of it must succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute. A creature repeats the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature’s saving throw is successful or the effect ends for it, the creature is immune to the dragon’s Frightful Presence for the next 24 hours.

Tidal Breath (Recharge 5-6). The dragon exhales a crushing wave of frigid seawater in a 90-foot cone. Each creature in that area must make a DC 23 Dexterity saving throw. On a failure, the target takes 44 (8d10) bludgeoning damage and 44 (8d10) cold damage, and is pushed 30 feet away from the dragon and knocked prone. On a successful save the creature takes half as much damage and isn’t pushed or knocked prone.

Legendary Actions

The dragon can take 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 dragon regains spent legendary actions at the start of its turn.

Detect. The dragon makes a Wisdom (Perception) check.

Tail Attack. The dragon makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 24 Dexterity saving throw or take 16 (2d6 + 9) bludgeoning damage and be knocked prone. The dragon can then move up to half its flying speed, or swim speed if in the water.

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