Well, you activate it by crushing the orb-shaped object you've been given. The healing itself... It just sort of comes to you. Like you'll know what to do when you really need it.

Also it has its limits. Its power seemed to fade after a couple months of not being used.

[She's lucky she was able to get what little she got out of it after being impaled.]

No one? Really? Huh. Used to listen to some opera that was pretty ancient.