You conjure a length of swaying, thorny vines with the head of a viper around yourself. When you cast this spell, you can make a melee spell attack with the vine against a creature within 10 feet of you. On a hit, the target takes 1d4 piercing damage and must make a Constitution saving throw. The creature takes 2d4 poison damage on a failed save, or half as much damage on a successful one.   Until the spell ends, you can repeat the attack as a bonus action on your turn.