Board Thread:General Discussion/@comment-67.70.92.41-20151228204640/@comment-4010415-20160226214314

Plasmarift wrote: 1. You can injure someone even if they are using their aura. It's happened enough times in the series already with Yang losing her arm, characters getting knocked out, getting brusies, and other stuff. Where does it say that a person can't be hurt if they have aura? Sure, they can use it to protect themselves, but it's just like using a shield; shields only cover so much and can only take so much damge before giving way. And I pointed out that Emerald made it look like Mercury wasn't expecting it, meaning he would be caught off guard and would not actively be protecting himself in any way using aura. In an interview, they said that the attack Adam used to cut Yang's arm off hit her so hard that it took out all of her Aura. It didn't cut through her Aura, it didn't injure her despite her having Aura. It straightup took her Aura down to 0% in one blow and cut her arm off. She had been fighting off-camera, and when Adam used his Semblance on her, he took her Aura the rest of the way down to 0%. (Source) However much she had left, his Semblance did more damage than it could take.

Getting knocked out isn't exactly an injury, per se. At least, I don't think it is.

As for where it says Aura protects a person from getting injured, I'll quote WoR: Aura:

"Aura is primarily used as a defensive mechanism. Passively coating the wielder in a protective force field, it can protect a combatant from what would normally be a fatal blow. It does not, however, make the user invincible. As they receive more and more damage, their Aura reserve will deplete. If this happens, all the fighter will be left with is his resolve."

Key word here being "passively", which means that, once someone unlocks their Aura, it automatically begins protecting them. They don't have to go "Oh, I'm about to be hit, better turn on my Aura!"

"It does not, however, make the user invincible" is referring to the fact that, with every hit they take, their Aura depletes, and if it hits 0, it can no longer protect them. The harder they're hit, the more Aura is depleted.