n tiny animal 

Perception +5; low-light vision

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] If a creature ends its movement adjacent to the viper or within the viper's space, the viper can use its reaction to Stride, Climb, or Swim up to 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) A target damaged by the viper's fangs must succeed at a DC 16 Fortitude save or take 1d10 poison damage.

Beginner Box, page 77. Reprinted in TiO.