Witch caress

This poison in the form of a colorless liquid is almost impossible to detect visually. It is easy to wash with water, which makes it immediately harmless. Some unscrupulous jewelers use it on their goods, in their safes or when traveling in unsafe areas.
A creature subjected to this poison must make a DC 12 Constitution saving throw, taking 4 (1d8) poison damage on a failed save, or half as much damage on a successful one.