These mysteriously-crafted alchemical poisons are designed to affect elementals and made only by the most capable of alchemists . When an elemental is subjected to one of these poisons, the poison affects the elemental as if it didn't have any immunity or resistance to poison or the poisoned condition.

Each poison is applied to a weapon -- one dose can coat one weapon or piece of ammunition. Applying the poison takes 1 minute. A creature that takes slashing or piercing damage from a weapon or pierce of ammunition coated with the poison is subjected to its effects.

Dire Fen Sludge (Injury). A creature subjected to this purple-black poison must make a DC 18 Constitution saving throw, taking 35 (10d6) poison damage on a failed save, or half as much damage on a successful one. Water elementals have disadvantage on the saving throw, and when a water elemental fails the saving throw, it is poisoned and can't use any abilities that recharge for 1 minute. It repeats the saving throw at the end of each of its turns, ending the effect on a success.

Notes: Damage: Poison, Poisoned, Consumable