A stuck door rimed with blue mold; the smell of mildew and dust mixes with a sickly sweet honey smell. Inside the room is blanketed with blue mold, organic shapes lumped beneath it. Breathing without protection in this room is laboured. Open flames in this room sputter and spark.

• Blue mold: malignant toxic mold. Consumes metal first, but will eventually devour organics.
• Organic shapes: under the mold, the bodies of dozens of serpent folk, partially consumed by the blue mold.
• Breathing: every turn spent breathing near the blue mold requires a Con save or take 1d4 Int damage. Any creature who reaches 0 Int becomes a mold zombie and will try to collect treasures and metals to feed to the mold colony. Zombies operate until the body dies of hunger, at which point it lays in the colony to be consumed.