Board Thread:General Discussion/@comment-98.215.58.230-20150210135957/@comment-3146930-20150210145641

A little of both actually. A Semblance is like the highest level of Aura, so using it for long periods of time would eventually drain your Aura and leave you more vulnerable. However it also appears to tire people out, as Ruby almost passed out when running with Penny. Weiss is also seen becoming tired after making several Glyphs to help Ruby drag the Nevermore up the cliff. However it seems like they recover fast enough.