Clot

You make a melee spell attack. If you hit a creature you cause its blood to solidify within its body, otherwise the spell is wasted.

The creature must make a Constitution saving throw. If the saving throw fails, the creature takes 12d6 necrotic damage and loses 2 points of Constitution. The target dies if this reduces its Constitution to 0. With a successful saving throw, the creature takes half damage and loses no Constitution. 

At the end of a long rest, the creature can repeat its saving throw against this spell. If it succeeds on its saving throw, the spell ends.

The spell can also be ended by lesser restoration, greater restoration, heal, or wish.