Board Thread:Off Topic/@comment-24534644-20170213012304/@comment-26397825-20170224002228

I came up with a theory that Semblance uses Aura, but in minuscule amounts at a time when using it at a level you are used to. As in, 0.5% for Yangs activation, which is how she could activate it in the fight against Mercury and not get disqualified for having her aura drop to 15%. It was still technically above it (by half a percentage) and the systems simply aren't sensitive enough to show that.

Pretty much my theory is that using your aura is like walking at a nice, sedate pace. You can do it all day, though eventually you will get tired, because a sedate pace doesn't use as much energy. However, pushing your semblance beyond the limits is like trying to sprint all day without being a trained sprinter; you quickly tire and end up being exhausted within a few minutes and have to rest to recover.

This parallels with how we saw Sun's aura disappear pretty quickly when he pushed his semblance beyond its limits against Ilia, but he could spam clones against the Sea Dragon with no worries. How initially, trying to move both herself and Penny made Ruby falter and fall without really getting anywhere, but she could spam her speed all day in fights.

Pushing your semblance of course allows you to get stronger, and the more you do it the more you can do with it before you burn out, sort of like a muscle. But pushing also burns through aura pretty quickly until your aura/body/whatever is used to the knee level of semblance manipulation you are doing, while using it at the level you are used to and not going beyond that only uses a tiny amount of aura each time.