Bukavac

Amphibious. The Bukavac can breathe air and water.

Hop. A bukavac can move its enormous bulk with remarkably quick hop of up to 20 feet, leaping over obstacles and foes. It may also use the hop as part of a Dash or Disengage action.

Multiattack. The bukavac makes four claw attacks, or two claw attacks and one bite attack

Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit:  (3d10 + 5) piercing damage, and the target is grappled (escape DC 16). Until this grapple ends, the target is restrained, and can't bite another target.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: (1d12 + 5) slashing damage.

Swallow. makes one bite attack against a Medium or smaller target it is grappling. If the attack hits, the target is swallowed, and the grapple ends. The swallowed target is blinded and restrained, it has total cover against attacks and other effects outside the Bukavac, and it takes 10 (4d4) acid damage at the start of each of the Bukavacs turns. The Bukavac can have only one target swallowed at a time. If the Bukavac dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone.

Croaking Blast (Recharge 5-6).. A bukavac can emit a howling thunderclap that deafens and damages those nearby. Creatures within 15 feet who fail a DC 17 Constitution saving throw take 36 (8d8) thunder damage and are deafened. Those succeeding on the saving throw take half damage and are not deafened. The deafness can be cured with lesser restoration.