When you cast this spell cast this spell, you must expend two hit die or else the spell fails.   You choose a target within range, marking their life force. A marked creature is forced to make a consitution saving throw once they have been marked. When a marked creature makes this saving throw, the DC has an initial bonus of +0. Upon a failure, the target takes Xd6 necrotic damage, where X is the number of hit dice expended to cast this spell. On the start of their turn while the spell is still active, the target must make this saving throw again, but the bonus to DC is decreased to +0, -1, -2, etc.   Once the target takes damage from this spell, that damage is then stored as hit points. Once this spell ends, you must transfer the total amount of hit points stored to another creature other than yourself within 30 ft.