Cleave Soul (Immortal Magic)

Expert Discipline: Spirit

You attempt to split the soul of a creature that you touch in two, causing one of the two effects detailed below:

Spirit Break. The target must make a Constitution saving throw equal to 5 + your spell save DC, taking 7d10 necrotic damage on a failed save, or half as much on a successful one.

Horcrux. The target must make a Constitution saving throw equal to your spell save DC. On a success, half of its soul is stored in the feather used in the casting of this spell. The next time the target would die, it instead drops to 0 hit points and is stable. If the target fails the saving throw, it takes 3d10 necrotic damage as its soul is fractured.