Aquatic Predator. Abyssodon can breathe only underwater.

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

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

Bite. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 36 (3d12 + 10) piercing damage. If the target is a creature, it is grappled (escape DC 23). Until this grapple ends, the target is restrained, and the Abyssodon Rex can't bite another target.

Tail Swipe. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 33 (3d10 + 10) bludgeoning damage.

Frightful Presence. Each creature of the Abyssodon's choice that is within 120 feet of the Abyssodon and aware of it must succeed on a DC 20 Wisdom saving throw or become frightened for 1 minute.

Whirlpool (Recharge 5–6). The Abyssodon can, as an action, create a whirlpool centered on itself. Each creature within 60 feet of the Rex must make a DC 23 Strength saving throw. On a failed save, a creature takes 48 (7d10 + 10) bludgeoning damage and is pulled 30 feet toward the Abyssodon.

Reaction Name. Enter the description for your action.

Tail Attack. The Abyssodon makes a tail attack

Sonic Roar (Costs 2 Actions): The Abyssodon Rex unleashes a deafening roar that resonates through the water and air, a sound born from the darkest depths of the ocean. The roar sends powerful shockwaves in a 60-foot radius from the Rex.

Each creature in that area must make a DC 20 Constitution saving throw. On a failed save, a creature takes 2d10 thunder damage and is stunned until the end of its next turn due to the disorienting sonic vibrations. On a successful save, the creature takes half as much damage and is not stunned.

Additionally, the roar creates ripples and currents that disrupt the water, imposing disadvantage on all attack rolls and ability checks made by creatures within the affected area until the end of the Abyssodon Rex's next turn.

Ink Cloud (Costs 2 Actions): The Abyssodon Rex releases a cloud of thick, dark ink from glands near its tail. This cloud spreads rapidly, covering a 30-foot radius around the Rex. The cloud remains for 1 minute or until a strong current disperses it. The ink is not only visually obstructive but also exudes a foul, nauseating stench.

The cloud heavily obscures the area, making it effectively impenetrable to vision, including darkvision. Creatures that start their turn in the cloud or enter it for the first time on their turn must make a DC 18 Constitution saving throw. On a failed save, a creature spends its turn retching and reeling (incapacitated) due to the overwhelming stench and is blinded until the start of its next turn. On a successful save, the creature is immune to the cloud's nauseating effects for 24 hours but remains blinded while within the cloud.