Vampire Bats

  "You know most bats aren't the Vamperic type" - Grell Ortho, Master Navigator

Upon casting this spell a plume of black smoke defused into a small cluster of shifting illusory bats.  Upon inhaling the smoke accompanying the bats the target makes a constitution saving throw to resist the effect of the spell or suffers 2d6 necrotic damage, half of that damage is stored as health in the smoke. That health may be called back to the caster or a  friendly ally within 15 feet of the original target healing them .  +1d6 when cast every level after the 2nd.