Black Bile (5e Equipment)
From D&D Wiki
Price per dose: 300 GP
Brewed from 5 Death Lily petals, 4 chinaberries, 6 castor beans, 1 oz of ghast blood, 4 mandrake roots, and 4 nightshade flowers on a successful DC 15 Wisdom(Poisoner's Kit) check.
Target must make a DC 17 Constitution Saving Throw. On a failure, they take 7(2d6) necrotic damage and their health is reduced by the same amount until they take a long rest. At the end of each of their subsequent turns, they make the saving throw again. On a fail, they're still poisoned and take an extra 2(1d4) necrotic damage. On a success, the effect ends.