Burnt othur fumes

inhaled (mixture) - 500 gp
MixtureA creature subjected to this poison must succeed on a DC 13 Constitution saving throw or take 10 (3d6) poison damage, and must repeat the saving throw at the start of each of its turns. On each successive failed save, the character takes 3 (1d6) poison damage. After three successful saves, the poison ends.
Dungeon Master´s Guide
  1. DnD 5e Poisons › Burnt othur fumes