Vampiric Link

Create a necrotic link between two creatures you can see. If a creature is not willing, it must make a Constitution saving throw. The spell fizzles out if both targets cannot be linked. However, if the spell is successful: When one of the linked creature damages the opposing linked creature, the spell absorbs 1d4+1 of the damage dealt (except radiant damage) and stores it. When a linked creature dies or goes unconscious the opposing linked creature (so long as it is conscious) is healed the amount of the stored damage that was dealt against it. The healed creature does not receive healing from the damage it dealt to the opposing linked creature.

If both creatures go unconscious before the spell can resolve: The links attached to both creatures explode (creating two different explosions) in a 20-foot-radius sphere dealing necrotic damage equal to the amount stored within each link.

Constructs are not affected by this spell.

At Higher Levels. When you cast this spell using a spell slot of 2nd level or higher, the spell absorbs an additional 1d4+1 for each slot level above 1st.