Exacerbate

You can curse the wounds spread about by battle, causing the bleeding to worsen. The targeted creature must make a Constitution saving throw. On a failure, the creature suffers 2d4 necrotic damage at the start of each of their turns and cannot regain Hit Points by any means for the spell's duration. The damage increases by 1d4 for each turn the spell persists. The creature may attempt to repeat this saving throw at the end of each of its turns, ending the spell on a successful save.