Amphibious. The kraken can breathe air and water.

Empowered Attacks. The kraken's weapon attacks count as magical for the purpose of overcoming resistance and immunity to nonmagical attacks.

Freedom of Movement. The kraken is immune to forced movement, ignores difficult terrain, and magical effects can't reduce its speed or cause it to be restrained or paralyzed.

Immutable Existence. The Kraken is immune to any spell or effect that would alter its form or send it to another plane of existence.

Innate Spellcasting. The kraken's spellcasting ability is Intelligence (spelll save DC 23). It can innately cast the following spells, requiring no components:

• at will: arcane eye, control winds, detect magic, dispel magic, nondetection, primordial ward
• 3/day: control weather, maelstrom, mass suggestion, scrying, tsunami (as an action), whirlwind
• 1/day: feeblemind, foresight, power word kill, storm of vengeance

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

Siege Monster. The kraken deals double damage to objects and structures.

Tentacles. The kraken has eight tentacles. A creature can attempt to attack a tentacle instead of damaging the kraken directly. If the creature deals  60 or more damage in a single turn to the tentacle, the kraken must succeed on a DC 25 Constitution saving throw at the end of that turn or let go of whatever it was grappling with that tentacle. If the creature deals 120 or more damage in a single turn to a tentacle or a character wielding a vorpal sword rolls a natural 20 for an attack against the tentacle, it is destroyed.

When a tentacle is destroyed, the number of attacks the kraken can make on its turn as well as the number of reactions it can take is reduced by one; if a creature does not manage to deal enough damage, the tentacle regenerates and heals off all damage dealt to it. A severed tentacle regrows after 7 days. If all tentacles are destroyed, the kraken dies.

Wrath of the Kraken. Whenever the kraken surfaces, churning storm clouds form in the sky within 1200 feet of it, gale-force winds howl, lightning flashes and thunder booms. The area becomes lightly obscured, any nonmagical flames are extinguished, ranged weapon attacks have disadvantage and any fog, mists, and similar phenomena in the area, whether mundane or magical, are dispersed automatically.

In addition, the sea within 1200 feet of it becomes rough. The water within that area counts as difficult terrain. Characters might experience strong, unexpected currents and high waves, resulting in ships capsizing or breaking apart and other dangers, on DM's discretion.

The effects disappear within ten minutes after the kraken dives again or dies.

Multiattack. The kraken can use its Terror of the Seas. It then makes one attack or uses Fling with each of its eight tentacles. The kraken cannot target the same creature or object more than once, unless it is huge or larger - in that case the kraken can target it with up to three tentacles.

Fathomless Maw. Melee Weapon Attack: [rollable]+18 to hit, reach 10 ft., one target. Hit: 59 (8d12+10) piercing damage and the target is swallowed by the kraken. While swallowed, a creature is blinded and restrained, it has total cover against attacks and other effects outside the kraken, and any swallowed creature or object takes 42 (12d6) acid damage at the start of each of the kraken's turns.

A swallowed creature is unable to sever the kraken's tentacles, no matter how much damage it deals.

If the kraken takes 60 damage or more on 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 10 feet of the kraken. If the kraken dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 15 feet of movement, exiting prone.

Tentacle. Melee Weapon Attack: +18 to hit, reach 120 ft., one target. Hit: 33 (4d12+10) bludgeoning damage, and the target is grappled (escape DC 26). Until this grapple ends, the target is restrained. The kraken has eight tentacles, each of which can grapple one target.

Fling. One object held or creature grappled by the kraken is thrown up to 3d6 × 10 feet in a random direction and knocked prone. If a thrown target strikes a solid surface, the target takes 3 (1d6) bludgeoning damage for every 10 feet it was thrown. If the target is thrown at another creature, that creature must succeed on a DC 19 Dexterity saving throw or take the same damage and be knocked prone.

Reel. The kraken pulls each creature grappled or object held with its tentacles up to 30 feet straight toward it.

All-Devouring Vortex (1/day). The kraken creates a massive whirlpool centered on itself, or rather on its maw. The whirlpool moves with the kraken, has a 600-foot radius, is up to 60 feet deep and lasts for up to 10 minutes, until the kraken dives again or until it dies. Any creature that starts its turn within the area of the whirlpool must make a DC 26 Strength saving throw. On a failure, it is pulled up to 60 feet straight toward the center of the whirlpool and takes 36 (8d8) bludgeoning damage as the raging sea hurls it around and waves crash onto it.

Ships fail the saving throw automatically, although it is up to the DM to decide by how far a ship of a certain size and speed is pulled each turn and if, and  how, this can be counteracted by the crew, such as by succeeding on skill checks to handle the ship.

Terror of the Seas. Any creature of the kraken's choice that is within 600 feet of the kraken and aware of it must succeed on a DC 23 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turn, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to this ability for the next 24 hours.

A creature that is captaining a ship within this area has disadvantage on the saving throw as it experiences visions of the kraken's enormous tentacles dragging down their beloved ship into the fathomless depths of the sea, just like it happened countless of times in old tales.

While Wrath of the Kraken is in effect, the kraken can take one of the following bonus actions on each of its turns:

Lightning Storm. The kraken can call down three lightning bolts, which strike three points within the area beneath the storm. Each creature within 10 feet of such a point must make a DC 26 Dexterity saving throw, taking 33 (6d10) lightning damage on a failed save, or half as much damage on a successful one. In addition, on a failed save, a creature cannot use reactions until the start of its next turn. The lightning bolts damage objects that are not being worn or carried within the area.

Tidal Wave. The kraken creates a massive tidal wave within 600 feet of it. The wave can be up to 120 feet long, up to 30 feet wide, and up to 30 feet tall. Each creature within that area must make a DC 26 Strength saving throw, taking 18 (4d8) bludgeoning damage on a failure or half as much on a success. In addition, on a failure, a creature is knocked prone. The wave damages objects that are not being worn or carried within the area.

The kraken can take eight reactions per round, one with each tentacle, although only one per turn.

Deflect Siege Missiles. The kraken uses a tentacle that is not grappling anything to block a large projectile thrown or shot by a siege weapon. The kraken must make a Strength (Athletics) check contested by the attack roll. On a success, it takes no damage from the attack as it successfully deflects the projectile.

Ship's Doom. When a ship leaves the kraken's reach, the kraken can use its reaction to make one tentacle attack against it.

The kraken can take 5 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. The kraken regains spent legendary actions at the start of its turn.

Insatiable Hunger. The kraken makes an attack with its fathomless maw.

Water Pulse. While in water, the kraken creates a pulse of water, propelling itself forward. Each creature that is within 30 feet of the kraken in the water must make a DC 26 Strength saving throw, taking 18 (4d8) bludgeoning damage on a failed save or half as much on a successful one. In addition, on a failed save, a creature is knocked prone. The kraken then moves up to half its speed.

Fathomless Magic (Costs 2 Actions). The kraken casts one of its spells.

Raging Storm (Costs 2 Actions). The kraken uses Lightning Storm or Tidal Wave.

Titan's Crush (Costs 2 Actions). Each creature restrained by the kraken must make a DC 26 Constitution saving throw. On a failure, it takes 36 (8d8) bludgeoning damage and has disadvantage on any ability checks it makes to attempt to escape from being restrained by the kraken until the end of its next turn. On a success, it takes half as much damage without any other effects.

Objects held by the kraken's tentacles take the damage automatically. If the kraken uses this ability to attempt to crush a ship held in its tentacles, everyone on board that ship must make a DC 18 Dexterity saving throw or is knocked prone.

Ink Cloud (Costs 3 Actions, Recharge 5–6). While underwater, the kraken expels an ink cloud in a 120-foot radius. The cloud spreads around corners, and that area is heavily obscured to creatures other than the kraken. Each creature other than the kraken that ends its turn there must make a DC 26 Constitution saving throw, taking 22 (4d10) poison damage on a failed save, or half as much damage on a successful one. A strong current disperses the cloud, which otherwise disappears at the end of the kraken's next turn