heres how id bring back azula
id make it that azula after begins to train her abilities while trying to build a cult for ozai figures out how to bend the brain electrical neurons essentially transfering all her memories between bodies as she is secretly planned to wipe out most benders have been wiped out by her after they reseruct vaatu through the corpse of ozai making him the new dark avatar frame it as korras fault and use him as the face of the cult which now rule the world