Stirge Swarm

You conjure a swirling swarm of magical Striges that swirl around within 20 foot radius of the target point. Creatures with blood other than the caster that start their turn within the area or enter it for the first time during a turn must make a Dexterity saving throw. On failure, they are drained of their blood by the swirling storm of Striges, reducing their hit points by 4d6 + 12 damage and restoring 4 hit points to the caster. On a successful save, they half as much damage and restore 2 hit points to caster.

As a bonus action on each of their turns for the duration of the spell, the caster and move the swirling swarm of Striges up to 30 feet in any direction.