Blood Rain

Throw a single drop of blood into the sky and choose a point within 120 feet. A 10-foot-tall, 60-foot-radius cylinder of blood-red clouds appears 100 feet above the ground at that point. The clouds begin to rain blood down below the cylinder. Each creature under the cloud is affected in one of two ways, your choice per creature. 
Bolstered: the creature gains 2d6 temporary hit points
Damaged: the creature must make a Constitution saving throw to take 2d6 necrotic damage.