Sea Dragon (5e Creature)
From D&D Wiki
Huge dragon, lawful evil
Saving Throws Dex +5, Con +11, Wis +7, Cha +9
Amphibious. The sea dragon can breathe air and water.
Frightful Presence. Each creature of the dragon's choice that is within 120 ft. of the dragon and aware of it must succeed on a DC 17 Wisdom saving throw or become Frightened for 1 minute. A creature can repeat 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.
Bite. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 18 (2d10 + 7) piercing damage.
Claw. Melee Weapon Attack: +12 to hit, reach 15 ft., one target. Hit: 16 (2d8 + 7) slashing damage.
The Adult Sea Dragon can take 1 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 Adult Sea Dragon regains spent legendary actions at the start of its turn.
Detect: The dragon makes a Wisdom (Perception) check.
The sea dragon is a large scaly blue serpent. It takes up quite a bit of space and can be a nightmare to sailors everywhere. Its hide is hard to pierce but can be done with some quick thinking. No one knows where they originally came from but nobody really cares when they're in the midst of sinking your ship.