Night's Wraith (5e Equipment)
From D&D Wiki
Price per dose: 150 gp
The poison makes the person who drinks it fall asleep. Night's wraith is a rare herb that requires a DC 20 Wisdom (Survival) check to locate. It is brewed at high temperatures with a small addition of wild fruit to disguise the bitter taste of the herbs.
The creature who ingests it must make a DC 10 Constitution saving throw, taking 7 (2d6) necrotic damage and falling asleep on a failure. The target takes half damage on a successful save and does not fall asleep.