Gibbering mouthers can speak Common, but seldom say anything other than gibbering.

Combat

Gibbering mouthers attack by shooting out strings of protoplasmic flesh, each ending in one or more eyes and a mouth that bites at the enemy. A mouther can send out a total of six such members in any round.

Gibbering (Su): As soon as a mouther spots something edible, it begins a constant gibbering as a free action. All creatures (other than mouthers) within a 60-foot spread must succeed at a Will save (DC 13) or be affected as though by a confusion spell for 1d2 rounds. This is a sonic, mind-affecting compulsion effect. Opponents who successfully save cannot be affected by the same gibbering mouther's gibbering for one day.

Spittle (Ex): At the start of every combat, and every 2 rounds thereafter, a gibbering mouther looses a stream of spittle. This ignites on contact with the air, creating a blinding flash of light. All sighted creatures within 60 feet must succeed at a Fortitude save (DC 13) or be blinded for 1d3 rounds.

Improved Grab (Ex): To use this ability, the gibbering mouther must hit with a bite attack.

Blood Drain (Ex): On a second successful grapple check after grabbing, that mouth attaches to the opponent. It automatically deals bite damage and drains blood, dealing 1 point of temporary Constitution damage each round. A mouth can be ripped off (dealing 1 point of damage) with a successful Strength check (DC 12) or severed by a normal attack that deals at least 2 points of damage (AC 18). A severed mouth continues to bite and drain blood for 1d4 rounds after such an attack. A creature whose Constitution is reduced to 0 is killed and absorbed by the mouther, which gains 1 hit point and adds another mouth and pair of eyes to its body.

Engulf (Ex): A gibbering mouther can try to engulf a Medium-size or smaller opponent grabbed by three or more mouths. The opponent must succeed at a Reflex save (DC 14) or fall and be engulfed. On the next round, the mouther makes twelve bite attacks instead of six (each with a +4 attack bonus). An engulfed creature cannot attack the mouther from within. The previously attached mouths are now free to attack others.

Ground Manipulation (Su): At will, as a standard action, a gibbering mouther can cause stone and earth within 5 feet of it to become a morass akin to quicksand. Softening earth, sand, or the like takes 1 round, while stone takes 2 rounds. Anyone other than the mouther in that area must take a move equivalent action to avoid becoming mired (treat as being pinned).

Amorphous (Ex): A gibbering mouther is not subject to critical hits. It has no clear front or back, so it cannot be flanked.

Skills: Thanks to their multiple eyes, gibbering mouthers receive a +4 racial bonus to Spot checks.