Deadwood Assassin

CR 5 (1,600 xp)

NE medium plant
Init +4; Senses Low-light vision; Perception +10

AC 16, touch 14, flat-footed 12 (+4 Dex, +2 natural)
hp 52 (7d8+21)
Fort +8, Ref +6, Will +5
Defensive Abilities plant traits
 

Speed 30 ft.
Melee +10 two claws (1d6+3)
 Space 5 ft.; Reach 5 ft.
Special Attacks Sneak attack +2d6
 

Str 17, Dex 18, Con 16, Int 13, Wis 16, Cha 15
Base Atk +5, CMB +8, CMD 22
Feats Weapon Finesse, Weapon Focus (claw), Improved Initiative, Improved Natural Attacks (claw)
Skills Perception +10, Stealth +10 (+14 in forests), Escape Artist +7, Survival +7
Languages Common, Sylvan

Environment any forests
Organization solitary or pair
Treasure standard

The deadwood assassin appears to be nothing more than a pile of wood and decaying plant matter until a creature gets too close to it (generally within 20 feet). It then assembles itself as a swift action and moves to attack the creature preferably using its sneak attack if it caught its foe off guard.