Audax (5e Creature)
From D&D Wiki
Huge beast, unaligned
Blood Frenzy. The audax has advantage on melee attack rolls against any creature that doesn't have all its hit points.
Hold Breath. While out of water, the audax can hold its breath for 30 minutes.
Water Breathing. The audax can breathe only underwater.
Damageable Plates. The heavy bones of the audax's face and spine are vulnerable to bludgeoning damage and will crack (turning to an AC of 13) if targeted in said area with a critical hit that deals bludgeoning damage.
Breath Sack. The audax possesses a large notably reddened organ inside their maw, that if ruptured with a well-placed attack or critical hit that deals piercing or slashing damage (DC 20+ on the face) will cause the creature to suffocate and die in 1d4 turns.
Bite Melee Weapon Attack: +9 to hit, reach 5 ft., one creature. Hit: 42 (6d12 + 6) piercing damage.
Steam Breath (Recharge 5-6). The audax exhales steam from its breath sack in a 15-foot cone. Each creature in that area must make a DC 12 Dexterity saving throw, taking 21 (6d6) fire damage on a failed save, or half as much damage on a successful one.
Stunning Tail Slap. Melee Weapon Attack: +5 to hit, reach 10 ft., one creature. Hit: 12 (2d10 + 1) bludgeoning damage. If successful the struck creature must roll a constitution save (DC 15) or be stunned for 1d4 turns
Crushing Blow. Melee Weapon Attack: +2 to hit, reach 5 ft., one creature. Hit: 26 (4d10 + 6) bludgeoning damage. If an opponent is struck with this blow they are crushed beneath the audax and must succeed on a DC 16 Dexterity saving throw or be trapped beneath the audax for another turn taking half the damage again for every turn trapped beneath it. If the audax moves off the square they occupied then they are freed from the damage.
Foul Progeny. A pregnant female audax, if struck with a critical hit or killed will release her spawn, which if exposed to water will hatch in 1d4 turns, if not exposed to water they will remain dormant and can be safely transported. audax eggs are produced under the armor that protects their mother's gills and are shot out the side of her face when its time to be born.
The audax is a spike-toothed fish monster related to the xiphactinus audax of ancient times that evolved functionality from estuaries to travel between waters of any type and even to hold its breath to travel across short distances of land in search of more fertile hunting grounds. They are large carnivorous beasts that prey upon anything smaller than they are, save their own kind. Rare and horrific, they are the terrors that decimate fish farms across nations, the horrors of the children's favorite lake, and the progenitors of unspeakable myths of riverboat massacres.
They look like immense hideously fang-faced tarpons with a hungering glow to their never closing eyes. The males are dark, with a sleeker build and thinner gills while the females are brightly colored when ready to mate and are far more muscular with immense armored gills for hiding their eggs and newborn offspring from predators. Their newborns look much the same as their parents only see-through in all but their armored plating and without the defined sexual dimorphism of their parents.
As predators, audax prefer to hunt in the dark, whether it be shadows, nightfall, or the caverns of the Underdark, so long as they have water (or a constant fog) they can and will go anywhere in their search for food.