Serpent venom

injury (venom) - 200 gp
VenomThis poison must be harvested from a dead or incapacitated giant poisonous snake.
A creature subjected to this poison must succeed on a DC 11 Constitution saving throw, taking 10 (3d6) poison damage on a failed save, or half as much damage on a successful one.
Dungeon MasterĀ“s Guide
5e tools