Gibbering Mouther

Gibbering Mouther CR: 2

Medium aberration, neutral

Armor Class: 9

Hit Points: 67 9d8+27

Speed: 10 ft , swim: 10 ft

STR

10 +0

DEX

8 -1

CON

16 +3

INT

3 -4

WIS

10 +0

CHA

6 -2

Damage Immunities: Prone

Senses: Darkvision 60 ft, passive Perception 10

Challenge Rating: 2

Aberrant Ground. The ground in a 10 foot radius around the mouther is doughlike difficult terrain. Each creature that starts it's turn in that area must succeed on a DC 10 Strength saving throw or have it's speed reduced to 0 until the start of it's next turn.
The mouther babbles incoherently while it can see any creatures and isn't incapacitated. Each creature that it's turn within 20 feet of the mouther and can hear the gibbering must succeed on a DC 10 Wisdom saving throw. On a failure, the creature can't take any reactions until the start of it's next turn and rolls a d8 to determine what it does during it's next turn. On a 1 to 4, the creature does nothing. On a 5 or 6 the creature takes no action or bonus action and uses all of it's movement to move in a randomly determined direction. On a 7 or 8, the creature makes a melee attack against a randomly determined creature within it's reach or does nothing if it can't make such an attack.

Actions

Multiattack. The gibbering mouther makes one bite attack and if it can, uses it's Blinding Spittle.
Bites. Melee Weapon Attack +2 to hit, reach 5ft, one creature. Hit 17 5d6 piercing damage. If the target is Medium, or smaller, it must succeed on a DC 10 Strength saving throw or be knocked prone. If the target is killed by this damage, it is absorbed into the mouther.
Blinding Spittle (Recharge 5-6). The mouther spits a chemical glob at a point it can see within 15 feet of it. The glob explodes in a blinding flash of light on impact. Each creature within 5 feet of the flash must succeed on a DC 13 Dexterity saving throw or be blinded until the end of the mouther's next turn.

Gibbering mouthers are accursed creatures created by foul sorcery. Absolutely disgusting to look at, they are a composite of eyes, mouths, and liquified matter of it's previous victims. Driven to insanity by the destruction of their bodies and absorption into the mouther, the creature gibbers incoherent madness, and forced to consume everything it reaches.
It is an amorphous blob of warped flesh, covered in mouths, and eyes, that hunts by crawling along the ground. Usually this is aided by the opening & closing oft the mouths, while twisted remnants of limbs help to drag it, while the bulk oozes along too. Water, mud or quicksand doesn't slow the advance. When it senses prey, it's mouths begin to murmur and chatter with each voice having a different timber. Some are wails of agony or ecstasy, and a few ranging in pitch between the two. The sight of it alone will cause a creature to flee or be paralyzed in terror, but the sound takes it to a whole new level. 
A gibbering mouther will consume anything it catches, leaving nothing behind except shredded clothing & gear. Once eaten, the victim is effectively turned into another part of the devourer, with the eyes & mouth being the only parts on display.

Suggested Environments

Ruins, settlements, sewers, crypts, forests, the Underdark.