When you, your familiar, or an Ally you can see within 30 feet of you takes damage, you can take a Reaction to cause that creature to regain a number of Hit Points equal to 1d10 plus your Charisma modifier.
Once you use this feature, you can't use it again until you finish a Short or Long Rest. You can also restore your use of it by expending a level 2+ spell slot (no action required).