Blood Tempest

You conjure a swirling storm of blood and shadow, lacerating and overwhelming your enemies within a raging sphere of necrotic energy. The storm appears in a 20-foot-radius sphere centered on a point you choose within range.

• Initial Laceration (When Cast): Each creature in the area must make a Dexterity saving throw. On a failed save, a creature takes 3d8 necrotic damage and 2d8 slashing damage as shadowy blades and congealed blood strike them. On a successful save, the creature takes half as much damage.
• Ongoing Assault (Each Turn): As a bonus action, you can direct the storm to lash out at one creature within the area. The target must make a Strength saving throw or take 2d8 necrotic damage and be pushed 10 feet in a direction of your choice.

The area of the storm is considered difficult terrain, and creatures in it are lightly obscured.

Empowered by Blood:

When you cast this spell, you can sacrifice hit points (up to 20). For every 5 hit points sacrificed, increase the damage of the initial laceration by 1d8 (to a maximum of 5d8 necrotic and 4d8 slashing).

At Higher Levels:

When you cast this spell using a spell slot of 5th level or higher, the damage of both the initial laceration and ongoing assault increases by 1d8 for each slot level above 4th.