I feel really stupid that I can't figure this out, but I've done several searches and nothing I've found is helpful.
I'm at the point where Erika told me to go to the hidden northeastern pathway and stand on the platform in the middle of the lava. I have the five brooches, the seal of the Empire, and the information from Aydin and Koth the dragon, which I believe is all I need. But I can't find where I'm supposed to be going. I thought it was Black Spire, but I still can't get through there. I read something about putting the Empire seal in the fresco, but when I approached it nothing happened.
Thanks in advance to anyone who can point me in the right direction.