Bottled Abyss

This small vial has a single dose of a fuming, pitch-black poison inside of it. When a creature eats or drinks the poison, it takes 4d6 psychic damage and must make a DC 18 Constitution saving throw. On a failed save, the creature becomes blind and unable to sleep. When an affected creature attempts to rest, their dreams are plagued with terrible nightmares, preventing them from benefiting from a long rest. The creature can reattempt the saving throw once every 24 hours.

The poison lasts until the affected creature succeeds on a saving throw or is cured by the greater restoration, heal, or wish spell.