Tail

Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 20 (3d10 + 4) bludgeoning damage plus 2 (1d4) poison damage. If the target is a Large or smaller creature, it must succeed on a DC 13 Strength saving throw or be knocked prone.

Rumbling Bellow (Recharge 5-6)

The mbielu releases a deep bellow that vibrates within the bodies of those nearby. Each creature within 15 feet of the mbielu must make a DC 13 Constitution saving throw, taking 18 (4d8) thunder damage on a failed save, or half as much damage on a successful one. If a creature poisoned by the mbielu's Toxic Skin fails this saving throw, it is also incapacitated until the end of its next turn as the combined vibrations and hallucinations disorient it.