This stone is tacky with a putrid green residue.

A blight stone creates an instantaneous burst of vapor that damages plants and plant-based creatures. The stone must be thrown (range increment 10 feet) or hurled from a sling (using that weapon’s normal range increment) as a ranged touch attack.
When the stone strikes its target or a hard surface, it deals no damage but explodes in a 10-foot-radius burst of noxious vapors. This cloud of gas deals 5d6 points of damage to all plants and plant creatures in the area (Fort DC 14 half).

Prerequisites: Craft Wondrous Item, blight.
Cost to Create: 150 gp, 12 XP, 1 day.