Agatha's Life Transference

You take some of an opponent's health that you can see within range to mend your own team's injuries. The creature must pass a CON saving throw, DC based on the user's spell save DC or 10 + their proficiency, or they take 2d6 necrotic damage, and one creature of your choice that you can see within range regains a number of hit points equal to the necrotic damage you made.

 At each additional level cast above 3rd level, add 1d6 necrotic damage and one additional creature to heal, splitting healing equally. If upcasted, overhealing results in temporary HP.