Heal Light 
Possible Target Types: SELF, ALLIES, VARIANT
Trigger actions: Getting attacked
BottledLight ingredient: minecraft:golden_apple
Conditions:
SELF:Low Health,Very low Health,Poisoned,Low armor durability,SurroundedALLIES:Ally's low Health,Very low Health,Ally Poisoned,Ally low armor durability,SurroundedVARIANT:Passive mob low Health,Passive mob or ally with Harmful potion effect,Harmful potion effect (self),Ally low health,Very low health
Effect:
SELF: When activated, the player will receive a Regeneration status effect, with power and duration equal to the player's power multiplier and duration attributes. Particles of Heal light will spawn around the player.ALLIES: When activated, any nearby allies with low health (or not, configurable in the config) will receive a Regeneration status effect, with power and duration equal to the player's power multiplier and duration attributes. The player will instead receive the same status effect but with the power reduced (configurable). Particles of Heal light will spawn around the player and allies.VARIANT: When activated, the player and any passive entity nearby will be cleansed of any harmful status effect (except LightFatigue), such as poison, weakness and such. Passive entities will also get the Regeneration effect. Particles of Heal light will spawn around the player and the entities.
Show Images

Demo video (a bit old)
Trivia: This was the first light that was developed!