Blood Bond (Sangromancy)

As part of casting this spell, you must expend three hit dice or the spell automatically fails. If you do, roll the expended hit dice, and a creature that is in possession of the rag soaked with your blood gains an equal number of temporary hit points. 

For the duration of the spell, you know the direction and distance to the creature at all times, you and the creature can speak to one another telepathically (provided the creature has an Intelligence score of 3 or higher) and you can target the creature with spells you cast that have a range of self or touch. These benefits are suppressed while you and the creature are not on the same plane. 

At any point, the creature affected by this spell can choose to end the spell early. If it does, the creature loses all remaining temporary hit points granted by this spell and takes necrotic damage equal to the temporary hit points lost. 

At Higher Levels. When you cast this spell using a spell slot of 5th or 6th level, its duration is 8 hours. When you cast this spell using a spell slot of 7th or 8th level, its duration is 24 hours. When you cast this spell using a spell slot of 9th level, its duration is 7 days.