Tempest: The Final Chapter - ROOT ABYSS!

Max says that the storyline ends with Damien leaving and then Demon Slayer/Avenger going, "Could that have been...?!?"

I am disappoint if that is the case.

It is the case currently, but as we've pretty much fought all of the Black Mage's commanders at some point or another sans Guwaru who was cutscene only it'd be weird to not have to fight him ever.