Styx

A potent memory-erasing drug, Styx forces a creature exposed to it to make a DC 14 Constitution saving throw or forget the last hour of their life. It can be injected or ingested. Multiple doses extend further back, and it is possible to wipe out weeks or even months of a creature’s memory with repeated or large doses. If a creature is subjected to additional doses within 1 hour of failing this saving throw, they must repeat the saving throw, losing an additional 1d4 days of memory on a failed save.