Freeddom of Movement. The Hydro ignores difficult terrain, and magical effects cannot reduce its speed or cause it to be restrained. It can spend 5 feet of movement to escape from nonmagical restraints or being grappled.

Multiattack. The Hydro makes three tentacle/claw attacks, any of which can be replaced by the bite or fling action

Bite. Melee Weapon Attack: +17 to hit, reach 5ft., one target. Hit 23 (3d8 + 10) piercing damage. If the target is Large or Smaller creature grappled by the Hydro, that creature is swallowed, and the grapple ends. While swallowed, the creature is blinded and restrained, it has total cover against attacks and other effects outside the Hydro, and it takes 42 (12d6) acid damage at the start of each of the Hydro's turns. If the kraken takes 50 damage or more during a single turn from a creature inside it, the kraken must succeed on a DC 25 Constitution Saving Throw at the end of that turn or regurgitate all swallowed creatures, which fall prone in a space within 10ft of the Hydro. If the Hydro dies a swallowed creature is no longer restrained by it and can escape from the corpse using 15 feet of movement, exiting prone.

Claw or Tentacle. Melee Weapon Attack: +17 to hit, reach 30ft., one target. Hit 5 (3d6 + 10)bludgeoning damage, and the target is grappled(escape DC 18).Until this grapple ends, the target is restained. The Hydro has 8 tentacles, only four can grapple if the Hydro is land.

Fling. One large or smaller object held or grappled by the Hydro is thrown up to 60ft in a random direction and knocked prone. If the target strikes a solid surface the target takes 3 (1d6) bludgeoning damage for every 10ft it was thrown. If the target is thrown at another creature, that creature must succed on a DC 18 Dexterity Saving Throw or take the same damage and be knocked prone.

Lighting Storm. The Hydro magically creates three bolts of lightning, each of which can strike a target the Hydro can see within 120ft of it. A target must make a DC 23 Dexterity Saving Throw, taking 22(4d10) lightning damage on a failed save, or half as much damage on a successful one.

Deplete Water. The Hydro magically drains the water out of a target it has grappled. As the water drains out of the creature or object, it must make a DC 25 Constitution saving throw, taking (10d10) necrotic damage on a failed save, or half as much damage on a success. Plant creatures and water-based elementals have disadvantage on this save. A nonmagical plant takes maximum damage from this spell. The Hydro regains Hp equal to a quarter of the amount of damage given to a target.

Legendary Actions

The Hydro can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creatures turn. The Hydro regains spent legendary actions at the start of its turn.