Wondrous Item, rare
A pale, odorless balm in a black tin wrapped in a ragged cloth. A player can take 5 minutes to coat one bladed weapon or five pieces of ammunition. For the next hour, a successful attack made with the coated weapon forces the target to make a DC 15 Constitution saving throw, taking 24 (7d6) poison damage on a failed save, or half as much damage on a successful one. Each tin has 1d4+2 uses available before it runs empty.