Venom Distillery

The south door is locked, and the lock contains a cleverly hidden poison needle trap. To pick the lock, a character with thieves’ tools must succeed on a DC 15 Dexterity check. Finding the trap requires a successful DC 20 Wisdom (Perception) check; once found, it can be disabled with a successful DC 12 Dexterity check. A character who tries to pick the lock without first disabling the trap must make a DC 16 Dexterity saving throw. On a failed save, the character is pricked by the needle, takes 5 (1d10) poison damage, and is blinded. The blindness is permanent but can be cured with a lesser restoration spell or similar magic.

The air in here is moist and sticky. Natural light spills from cracks in the ceiling, and mud coats the floor. Stone workbenches are laden with clay bottles of various shapes and sizes. Toadstools, snakeroot, and belladonna plants grow among the clutter, fed by water seeping from above. Standing near the plants is a hairless man with scaly skin and a bronze syringe. Lurking in the shadows around him are five slouching humans that reek of decay.

Yuan-ti use this chamber to extract venom from snakes. Xopal (pronounced zoh-PAUL), a yuan-ti pureblood, bottles and blends the venom to create deadly new strains. Five human zombies serve Xopal as laborers.
Xopal carries a bronze syringe containing three doses of a poison cocktail. As an action, he can make a melee weapon attack with the syringe (+3 to hit), which deals 1 piercing damage and injects one dose of poison on a hit. Any creature injected with a dose of poison must make a DC 14 Constitution saving throw, taking 10 (3d6) poison damage on a failed save, or half as much damage on a successful one. In addition, the creature is poisoned for 1 hour whether or not its save succeeds.
Xopal believes it’s his destiny to transform into a much more powerful form of yuan-ti — a metamorphosis that will occur when he develops a poison so virulent that even innate immunity to poison can’t withstand it. Xopal uses the zombies as test subjects; once he’s overcome their immunity, he plans to conduct further tests on live yuan-ti.
Bottled Poisons
The presence of so many poisons makes combat in this room hazardous. If a workbench is exposed to explosive force, such as that generated by a thunderwave or fireball spell, the bottles smash and create a 15-foot-radius sphere of poisonous vapors that lasts for 1 minute. Any creature that enters the area for the first time on a turn or starts its turn within the sphere must make a DC 15 Constitution saving throw, taking 18 (4d8) poison damage on a failed save. Creatures are affected even if they hold their breath or don’t need to breathe.
Among the poisons is a stoppered bronze jug used for fermenting jungle roots into soporific gas. Removing the stopper releases the gas, which fills a 15-foot-radius sphere centered on the jug. See area 3 for the effect of the soporific gas.
Treasure
Xopal carries a brass key that unlocks the south door.
Characters who search through the poisons can loot twenty doses of serpent venom, five doses of essence of ether, and five doses of torpor (see “Poisons” in chapter 8 of the Dungeon Master’s Guide).