Merwyrm (5e Creature)
From D&D Wiki
Large dragon, chaotic evil
Amphibious. The merwyrm can breathe air and water
Stench of the Deep. The air around this beast is filled with an unholy stench of rotting flesh and the brackish filth of the deepest sea abysses. Any creature other than a merwyrm that starts its turn within 5 feet of the merwyrm must succeed on a DC 13 Constitution saving throw or be poisoned until the start of the creature's next turn. On a successful saving throw, the creature is immune to the stench of all merwyrms for 1 hour.
Multiattack. The merwyrm makes three attacks: one with its bite and two with its claws or with its tail.
Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (2d8 + 4) piercing damage and the merwyrm regains hit points equal to half the total damage dealt.
Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., Hit: 8 (1d8 + 4) slashing damage.
Tail. Melee Weapon Attack: +7 to hit, reach 10 ft., one target. Hit: 9 (1d10 + 4) bludgeoning damage.
Cold Breath (Recharge 6). The merwyrm exhales freezing deep ocean cold in a 25-foot cone. Each creature in the area must make a DC 15 Constitution saving throw or take 27 (6d8) cold damage on a failed save, or half as much damage on a successful one.
Merwyrms are found along the coastlines the world, distant kin to the mighty winged dragons that once ruled the skies. Loremasters believe that their scaled forms once swarmed in the primordial oceans of the world, but they are now rarely heard of save in tales of embittered sailors who claim to have lost ships and crewmates to these beasts.
Ruthless Hunters. All merwyrms possess long, almost serpentine and sinuous bodies covered in scales and corded with muscle, with four stubby limbs each tippped with razor-sharp claws. Unlike dragons, the more primitive merwyrms do not possess wings, the lashing of their bodies serving to propel them through the deeps at great speed or with a frightening gait across dry ground when their hunger takes them there to pursue prey; much to the dismay of any who believe they might easily escape by taking to land.
Terror from the Deeps. Merwyrms are hardy and adaptable creatures, their bodies able to heal at a tremendous rate, fuelling their never-ending hunger and endless search for food. They also carry within themselves the killing cold of the depths where light never reaches, and are able to exhale a chill force in deadly blasts to enfeeble and slay its warm-blooded prey, before devouring them with its hideous fang-filled jaws.
Varied Species. Merwyrms are most commonly found in the dangerous coastal waters of the Sea of Claws, and are bright silver-green and can be highly venomous. When food is scarce they have been known to assault coastal villages, devouring their inhabitants.