Fangs of the Serpent

The Yuan-ti develops retractable hollow snake fangs and a poison gland in their neck. The Yuan-ti can make a bite attack as a bonus action. The bite attack uses Dexterity as the primary stat and deals 1d4 piercing damage and 2d6 poison damage to the target on a successful hit. They can also use their venom gland to apply poison to their weapon as a bonus action. They can use their poison a number of times per day equal to their proficiency bonus. A envenomed weapon causes their next successful weapon attack to deal an additional 2d6 poison damage. Once they have used the poison for a successful hit it does not deal that damage again on further attack without applying more poison.