Sickening Sleep (CR 2)

Medium Ooze
Alignment: Always neutral
Initiative: -1 (Dex)

AC: 10 (-1 Dex, +1 deflection), touch 10, flat-footed 10
Hit Dice: 1d10 (5 hp); DR: 10/magic
Fort +1, Ref +0, Will +0
Speed: 20 ft.
Space: 5 ft./5 ft.
Base Attack +0; Grapple +0
Attack: Slam +0 melee
Full Attack: Slam +0 melee
Damage: Slam 1d4 plus enfeeblement and sleep
Special Attacks/Actions: enfeeblement, engulf, sleep
Abilities: Str 11, Dex 8, Con 11, Int -, Wis 8, Cha 11
Special Qualities: ooze traits, SR 11
Feats: -
Skills: -
Advancement: -
Climate/Terrain: underground
Organization: solitary
Treasure/Possessions: none

Source: Monster Manual III

Engulf (Ex): a sickening sleep can flow around creatures that fit within its space as a standard action. It cannot make a slam attack during a round in which it engulfs. A sickening sleep merely has to move over the opponents, affecting as many as it can cover. Opponents can make attacks of opportunity against a sickening sleep, but if they do so they are not entitled to a saving throw. Those who do not attempt attacks of opportunity must succeed on a DC 11 reflex save or be engulfed; on a success, they are pushed back or aside (opponent's choice) as the spell moves forward. Engulfed creatures are subject to the ray of enfeeblement and sleep effects and are considered to be grappled.

Ray of enfeeblement (Su): a creature hit by a sickening sleep's slam attack or engulfed by it takes a 1d6 penalty to strength for 1 minute. Multiple hits are nor cumulative, and the subject's strength score cannot drop below 1.

Sleep (Su): a creature hit by a sickening sleep's slam attack or engulfed by it falls asleep for 1 minute (will DC 11 negates).

A sickening sleep is often encountered in dank underground passageways.