I have a question...?

Wait a minute.....

Did I miss something? Or am I forgetting something? Who is Jang Gang in the end? I mean the late emperor performed the AoS and turned into Jang Gang and with Lady Dohwa had Jang Uk- that's fine BUT— who is the Jang Gang who blocked Jang UK's torrent of energy and then disappeared into thin air voldemort style? Did I miss something? Does he turn back into himself?