Druidic. Each beast within 120 ft. and is aware of the abyss eater must make a DC 18 Wisdom saving throw. On a failed save, the beast is charmed until the abyss eater attacks it, on a successful save the beast is immune to the effect for 24 hours.

Amphibious. The abyss eater can breath air and water.

Siege Monster. The abyss eater does double damage to objects and structures.

Water Wings. The abyss eaters fins produce a constant current of water as long as it is fully submerged. To each side of the abyss walker, there is wall of water 5 ft. long, 5 ft. high, and 1 foot thick. Each creature in its area must make a DC 17 Strength saving throw. On a failed save, the target takes 17 (3d8 + 3) Bludgeoning damage and is pushed 10 ft. back. On a successful save, the target takes half the damage and is not moved.

Disruptive Presence. The abyss eater displaces so much water when it swims, it creates a strong current. Wherever the abyss eater swims a current is left there until the end of its next turn. Each creature that enters the currents area must make a DC 13 Athletics saving throw. On a failed save, the creatures swim speed is halved until the end of its next turn, on a successful save the creatures swim speed is increased by 10 ft. until the end of its next turn.

Multiattack. The abyss eater uses its water pulse if it can, then attacks with Surge.

Surge. Melee Weapon Attack: +7 to hit, reach 10 ft. cube, all targets. Hit: 22 (4d8 + 4) bludgeoning damage. 

Water Pulse (Recharge 5-6). The abyss eater floods the area surrounding it in a 40 ft. radius centered on itself. Each creature in the radius makes a DC 17 Strength saving throw. On a failed save, the creature takes 17 (3d8 + 3) Bludgeoning damage and is pushed 10 ft. back. On a successful save, the creature takes half the damage and is not moved. If used on land, all open flames in the radius are extinguished and the water remains on the ground.