Multiattack

The gibbering mouther makes two Bite attacks. If both attacks hit one Medium or smaller creature, the target must succeed on a DC 13 STR save or be knocked prone.

Bite

_Melee Weapon Attack:_ +4 to hit, reach 5 ft., one creature. _Hit:_ 11 (2d8+2) piercing damage.

Rend Mind

One creature the mouther can see within 30 feet of it must succeed on a DC 13 WIS save or take 18 (4d8) psychic damage and suffer a random, short-term dread effect for 1 minute