Mbielu

A creature that touches the mbielu or hits it with a melee attack exposes itself to the mbielu's poisonous skin. The creature must succeed on a DC 13 Constitution saving throw or be poisoned for 1 minute. While poisoned in this way, a creature also suffers disadvantage on Intelligence, Wisdom, and Charisma saving throws.

Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 20 (3d10 + 4) bludgeoning damage. If the target is a creature, it must succeed on a DC 14 Strength saving throw or be knocked prone.

If the mbielu is grappled by a Large creature, it rolls on top of the grappler and crushes it. The mbielu automatically escapes from the grapple and the grappler takes 20 (3d10 + 4) bludgeoning damage.