Blood Frenzy. The Aberrant Beast has advantage on melee attack rolls against any creature that doesn't have all its hit points.

Amphibious. The Aberrant Beast can breathe air and underwater.

On its turn the Aberrant Beast can choose to use either its claws or tentacles to attack, not both.

Tentacle. Melee Weapon Attack: +6 to hit, reach 15 ft., one target. Hit: 7 (1d8+3) piercing damage.

If the target is Medium or Smaller, it is grappled (escape DC 13) and restrained until the grapple ends. The Aberrant Beast can use two tentacles, each of which can grapple one target.

Claw. Melee Weapon Attack: +3 to hit, reach 15 ft., one target. Hit: 4 (1d6+1) bludgeoning damage, and the target is grappled (escape DC 11). The Aberrant Beast can use two claws, each of which can grapple one target.

Psychic Lance. The Aberrant Beast magically emits psychic energy at a creature is sees within a 60-foot from it. The target must succeed on a DC 12 Constitution saving throw or take 6 (2d6) psychic damage.

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 22 (3d10 + 6) piercing damage.