Amphibious. The aberrant kraken can breathe air and water.

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

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

Creature Sense:  The aberrant kraken is aware of the presence of creatures within 5 miles of it that have an Intelligence score of 4 or higher. It knows the distance and direction to each creature, as well as each one's Intelligence score, but can't sense anything else about it. A creature protected by a mind blank spell, a nondetection spell, or similar magic can't be perceived in this manner.

Innate Spellcasting. The aberrant kraken's innate spellcasting ability is Intelligence (spell save DC 22, +19 to hit with spell attacks). It can innately cast the following spells, requiring no material components:

At will: detect thoughts

3/day each: mind spike, confusion

1/day each: dominate monster, feeblemind, plane shift (self only)

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

Magic Resistance. The aberrant kraken has advantage on saving throws against spells and other magical effects.

Multiattack. The aberrant kraken makes three tentacle attacks, each of which it can replace with one use of Fling.

Bite. Melee Weapon Attack: +18 to hit, reach 5 ft., one target. Hit: 28 (3d10 + 10) piercing damage and 14 (4d6) psychic damage. If the target is a Large or smaller creature grappled by the aberrant kraken, 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 aberrant kraken, and it takes 42 (12d6) acid damage at the start of each of the aberrant kraken's turns.

If the aberrant kraken takes 50 damage or more on a single turn from a creature inside it, the aberrant 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 aberrant kraken. If the aberrant 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: +17 to hit, reach 30 ft., one target. Hit: 23 (3d8 + 10) bludgeoning damage and 7 (2d6) psychic damage, and the target is grappled (escape DC 18). Until this grapple ends, the target is restrained. The aberrant kraken has ten tentacles, each of which can grapple one target.

Fling. One Large or smaller object held or creature grappled by the aberrant kraken is thrown up to 60 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.

Lightning Storm. The kraken magically creates three bolts of lightning, each of which can strike a target the kraken can see within 120 feet of it. A target must make a DC 22 Dexterity saving throw, taking 22 (4d10) lightning damage on a failed save, or half as much damage on a successful one.

Mind Blast (Recharge 5-6). The aberrant kraken magically emits psychic energy. Creatures of the aberrant kraken's choice within 60 feet of it must succeed on a DC 22 Intelligence saving throw or take 51 (8d10 + 15) psychic damage and be stunned for 1 minute. A target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

The aberrant kraken can take 3 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 aberrant kraken regains spent legendary actions at the start of its turn.

Tentacle Attack or Fling. The aberrant kraken makes one tentacle attack or uses its Fling.

Lightning Storm (Costs 2 Actions). The aberrant kraken uses Lightning Storm.

Mind Blast (if Charged, Costs 3 Actions). The aberrant kraken uses Mind Blast.

Ink Cloud (Costs 3 Actions). While underwater, the aberrant kraken expels an ink cloud in a 60-foot radius. The cloud spreads around corners, and that area is heavily obscured to creatures other than the aberrant kraken. Each creature other than the aberrant kraken that ends its turn there must succeed on a DC 23 Constitution saving throw, taking 16 (3d10) 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 aberrant kraken's next turn.