Vampiric Drain

Your consume a creature's life and inflicts disease simultaneously. Make a ranged spell attack against a creature within reach. On a hit, the target take 1d6 necrotic damage, you gain temporary hitpoints equal to the damage.

If the target is a humanoid, the target must make a Constitution saving throw(DC7), if the target fails, they are inflicted with Sanguine Vampiris, the creature has 3 days to cure themselves of this disease, failure to do so and the creature will mutate by this disease and become a Lesser Vampire Spawn, gaining it's abilities but vulnerabilities as well, see the Vampire Spawn Stat Block as reference.

A Lesser Vampire Spawn will have no master, and cannot be controlled by any vampire, including the caster of this spell, after becoming a spawn, they will go into a blind frenzy indefinitely, attacking and feasting on any creatures they can find and spells can only stop the frenzy temporarily.