Cairath

Animalistic intellect: Cannot be blinded, charmed, deafened, frightened, or poisoned.

Growth Spurt: Once the cairath has consumed five corpses, it grows in size, increasing its damage output per attack by an additional 1d4 and gaining additional 25 hit points.  Once it has grown in size twice, it can do so no more (from medium, to large, and finally to huge).

Many Arms: The cairath's body is comprised of numerous writhing limbs, making it difficult for creatures to grapple or escape its grasp. Creatures that attempt to grapple the cairath or escape from its grapple have disadvantage on their checks.

Multiattack: The cairath makes four melee attacks using Slam.  It can use its Devouring ability once a turn in place of two melee attacks.

Slam. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 4 (1d4 + 2) bludgeoning damage.

Devouring: As an action, the cairath can consume a nearby corpse to replenish its lost life force (2d4+4 hit points).

Coordinated Burst (1/day): As a bonus action, the cairath's multiple arms move in perfect unison, granting it a burst of incredible speed and devastating power. Its speed increases to 60 feet, and it can unleash a flurry of 8 slam attacks on its turn, each strike hitting with deadly precision. This effect lasts until the end of the cairath's current turn.