In the past week I have seen multiple fanfic authors say a character handled a bad situation by diffusing it.
Please don't have your characters diffuse things unless they're adding sugar to their coffee or putting a toxic gas in the ventilation system.
I think this was probably early 2000's. In this fantasy novel the way wizard magic works is they are somehow mystically linked to another person, identity normally unknown, and when they use magic it actually drains that person's life force. When they run out, they die. The link then jumps randomly to some other person.
I believe this normally was restricted to men (maybe women could use magic too but were unlinked so would drain their own energy and die sooner?). The main character is a woman who finds out she is able to use magic like the wizards do. I believe it was a secret that wizard magic worked like this because otherwise killing wizards might seem like a good idea. The main character is unhappy to find out the truth. I believe she discovered that she was linked to someone that she knew. Unfortunately I don't remember the rest of the plot.