You point at any location (a jar, a bowl, even a puddle) within range that contains at least a pint of blood. Each creature that feeds on blood and is within 60 feet of that location must make a Charisma saving throw. (This includes undead, such as vampires.) A creature that has Keen Smell or any similar scent-boosting ability has disadvantage on the saving throw, while undead have advantage on the saving throw. On a failed save, the creature is attracted to the blood and must move toward it unless impeded. Once an affected creature reaches the blood, it tries to consume it, foregoing all other actions while the blood is present. A successful attack against an affected creature ends the effect, as does the consumption of the blood, which requires an action by an affected creature.