UPDATED:
Death Saving Throws
When you start your turn with 0 Hit Points or take damage while at 0 Hit Points, you make a DC 10
Death Saving Throw to determine if you creep closer to death or hang on to life. Unlike other saving throws, this one isn’t tied to an ability score. You’re in the hands of fate now.
If you take damage from a Critical Hit while at 0 Hit Points, you make the Death Saving Throw with Disadvantage.
Success. You keep death at bay for the moment. You are Stable (see below).
Failure. Until the end of your next turn, your Speed is 0 and you have the Stunned Condition.
Failure/Stunned. If you fail a Death Saving Throw while Stunned, you have the Unconscious condition until you regain any Hit Points.
Failure/Unconscious. If you fail a Death Saving Throw while Unconscious, you die.
Stabilizing a Character
You can take the Help action to try to stabilize a creature with 0 Hit Points, which requires a successful DC 10 Wisdom (Medicine) check.
A
Stable creature doesn’t make Death Saving Throws even though it has 0 Hit Points at the start of its turn. If the creature takes damage, it stops being Stable and starts making Death Saving Throws again.
A Stable creature that isn’t healed regains 1 Hit Point after 1d4 hours.
I think that should do it for you
@Charlaquin, barring any additional rules for things like other magical items, etc.