n tiny animal 

Perception +5; low-light vision, scent (imprecise) 30 feet

Skills Acrobatics +5, Athletics +1 (+4 to Climb), Stealth +5, Survival +3

Str -3 Dex +4 Con +0 Int -4 Wis +1 Cha -2

AC  15; Fort +2, Ref +7, Will +5

HP 8

Slink [R] Trigger A creature ends its movement adjacent to the viper or within the viper's space. Effect The viper Strides, Climbs, or Swims up to 10 feet (or up to the relevant Speed, if that Speed is less than 10 feet). It must end its movement in a location that isn't within 5 feet of a foe. This movement doesn't trigger reactions.

Speed 20 feet, climb 20 feet, swim 20 feet

Melee [>] fangs +8 (agile, finesse), Damage 1d8-3 piercing plus viper venom

Viper Venom (poison) Saving Throw DC 16 Fortitude; Maximum Duration 4 rounds; Stage 1 1d8 poison. (1 round)

Bestiary, page 302.