Triage

You focus your concentration on a living creature you can see within range.

While you maintain concentration, you or the creature you are concentrating on may use your respective reactions on the start of its turn, before Death Saves are rolled or any other effects take place, to spend 1 Hit Dice (or up to 2, if the Hit Dice is a D6) and heal the target creature by the amount rolled on that dice without con bonuses. If the target creature is at 0HP, and has no failed Death Saves, you may use your reaction to spend the target's Hit Dice instead.

The spell's range increases to 15ft when you reach 5th level, 11th level increases the range to 30ft, and 17th level increases the range to 60ft.