Dark Creeper (CR 3)

Small Humanoid
Alignment: Usually chaotic neutral
Initiative: +3 (Dex); Senses: blindsight 60 ft., Listen +3, and Spot +3

AC: 17 (+1 size, +3 Dex, +2 leather armor, +1 natural), touch 14, flat-footed 14
Hit Dice: 1d8+1 (5 hp)
Fort +1, Ref +7, Will +2
Speed: 30 ft.
Space: 5 ft./5 ft.
Base Attack +0; Grapple -3
Attack: Dagger +2 melee, or dagger +2 ranged
Full Attack: Dagger +2 melee, or dagger +2 ranged
Damage: Dagger 1d4+1
Special Attacks/Actions: Shadow cloak, sneak attack +2d6
Abilities: Str 12, Dex 17, Con 13, Int 10, Wis 13, Cha 10
Special Qualities: evasion, light sensitivity
Feats: Lightning Reflexes
Skills: Hide +8*, Listen +3, Move Silently +4, Sleight of Hand +4, Spot +3, and Tumble +6
Advancement: By character class
Climate/Terrain: Any underground
Organization: Solitary, band (2-5 plus 1 dark stalker), or tribe (20-80 plus 2-5 dark stalkers)
Treasure/Possessions: Standard

Source: Fiend Folio

Evasion (Ex): If exposed to any effect that normally allows a Reflex save for half damage, a dark creeper takes no damage on a successful saving throw.

Shadow Cloak (Su): Three times per day, a dark one can wrap itself in a cloak of shadows that grants it concealment from its foes. In shadows or darkness, the shadow cloak gives the creature nine-tenths concealment (40% miss chance for attackers). In bright light, the shadow cloak provides only one-half concealment (20% miss chance). Darkvision does not negate the dark one's concealment, since the shadow cloak is formed from magical darkness. Creatures that can see in magical darkness, such as devils, do not have a miss chance when striking a dark one.

Sneak Attack (Ex): Anytime a dark one's target is denied a Dexterity bonus, or when a target is flanked by a dark one, the dark one deals additional damage on a successful melee attack. Dark creepers deal an additional 2d6 points of damage, and dark stalkers deal an additional 3d6 points of damage.

Blindsight (Ex): A dark one maneuvers and fights not only by sight, but also by using hearing and smell to ascertain its surroundings. This ability enables it to discern objects and creatures within 60 feet. A dark one usually does not need to make Spot or Listen checks to notice creatures within range of its blindsight.

Light Sensitivity (Ex): When exposed to sunlight, or to light equivalent to a daylight spell, a dark one takes a -2 morale penalty on all attacks, saves, checks, and damage rolls.

Skills: When in shadowy areas, a dark one has a +8 racial bonus on Hide checks and a +4 racial bonus on Move Silently checks.

Dark ones are extremely stealthy, but cowardly. They prefer to fight under the cover of complete darkness and flee when the odds turn against them. They are masters of ambush and often pick off individuals from the shadows.

Dark creepers hide in shadows before attacking the exposed flank and rear of their opponent.