Crimson Blight

You unleash a wave of necrotic energy, saturating a 20-foot-radius sphere centered on a point you choose within range. The corrupted area is imbued with blood magic that weakens and saps the vitality of those within.

Effects:

When a creature enters the area for the first time on a turn or starts its turn there, it must make a Constitution saving throw.

• On a failed save, the creature takes 5d10 necrotic damage and is afflicted with Crimson Decay for 1 minute. While afflicted, the creature has disadvantage on attack rolls and ability checks, and its movement speed is halved.
• On a successful save, the creature takes half as much damage and is not afflicted with Crimson Decay.

A creature afflicted with Crimson Decay can make another Constitution saving throw at the end of each of its turns, ending the effect on itself on a success.

Empowered by Blood:

When casting this spell, you can sacrifice hit points (up to 20). For every 5 hit points sacrificed, increase the necrotic damage by 1d10 (to a maximum of 7d10).

At Higher Levels:

When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d10 for each slot level above 4th.