Bare Minimum

Prepared beforehand, you take the stomach of a flying snake and fill it with salt and ground up snake plant, and then tie it shut. (Colloquially known amongst healers as a "snake sack" or "snake bomb".)

If an ally within 30 feet of you drops to 0 or lower hp, use your reaction to throw one of these snake sacks at them. (No need for a roll.) Once it hits, it stabilizes them at one hit point and returns them to consciousness.

(Does not effect dead, undead, constructs.)