Carnageclaw

Rampage: When Carnageclaw reduces a creature to 0 hit points with a melee attack on its turn, it can take a bonus action to move up to half its speed and make a bite attack.

Keen Smell: Carnageclaw has advantage on Wisdom (Perception) checks that rely on smell.

Multiattack: Carnageclaw makes three attacks: one with its bite and two with its claws.

Bite: Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 16 (2d8 + 5) piercing damage. If the target is a creature, it must succeed on a DC 15 Strength saving throw or be grappled (escape DC 15). Until this grapple ends, the target is restrained, and Carnageclaw can't bite another target.

Claw: Melee Weapon Attack: +8 to hit, reach 5 ft., one target. Hit: 14 (2d6 + 5) slashing damage.

Swallow: Carnageclaw makes one bite attack against a Medium or smaller grappled creature. If the attack hits, the target is swallowed, and the grapple ends. The swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside Carnageclaw, and it takes 21 (6d6) acid damage at the start of each of Carnageclaw's turns. If Carnageclaw takes 30 or more damage on a single turn from a creature inside it, Carnageclaw must succeed on a DC 15 Constitution saving throw at the end of that turn or regurgitate the swallowed creature, which falls prone in a space within 10 feet of Carnageclaw. If Carnageclaw dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 30 feet of movement, exiting prone.

Brutal Counter: When Carnageclaw is hit by a melee attack, it can make a claw attack against the attacker as a reaction.