This elegant, stoppered glass bottle holds a dark, viscous fluid.

One round after you apply this elixir to your skin, it creates an invisible cloud of gas in a 10-foot radius that moves with you and persists for 1 minute. You are immune to the cloud’s effects, but every other creature in the area that has 3 Hit Dice or fewer immediately dies (no save). A creature that has 4–6 Hit Dice must succeed on a DC 17 Fortitude save each round it remains in the area or die. A creature that has 7 Hit Dice or more takes 1d4 points of Constitution damage (Fort DC 17 half) per round of exposure.
If you open the bottle but do not immediately apply the liquid, the cloud of gas spreads to fill a 5-foot-radius area, centered on the opened bottle or the place where the liquid was poured out. This cloud persists for 1 minute.

Prerequisites: Craft Wondrous Item, cloudkill, Craft (alchemy) 4 ranks.
Cost to Create: 2,000 gp (plus 500 gp for base item), 160 XP, 4 days.