Who's ready for the DRAGONIC SWORD!?!

Based on what I can see from the other stuff on Max's blog, I'm gonna guess it's the final fight against the Black Mage himself. But it'll take the form of two separate fights as one - in other words, we'll fight Herr Magnus first, then we'll face off against the Black Mage himself in truest final boss fashion.

I mean, that Black Mage silhouette looks mightily intimidating. Why else would they throw him there out of the blue, and not just throw Magnus into the room?

This is heavily starting to smell like Megaman X. Except I doubt we'll be fighting a normal form of Black Mage and skip straight to his Nitemare form.

Basically, in a nutshell:

Magnus = Velguader
Black Mage = Velguader Sigma

In other words, we'll be skipping a phase of the whole Sigma fight (except it's Maple and the Black Mage) - and from the looks of things, it sounds like one of their devs was spending his night shift playing Megaman X the entire time.

Also, the presence of Mercedes, Evan, and Demon Slayer could signal that their little "grudge matches" didn't quite end up the way they had anticipated (I think mostly because they didn't expect Magnus to come butting in).

or it could be a quest to save Mercedes, freed, and demon slayer? I can see how maplers get a quest from Cygnus to try and go save them. the black Mage, wanting some entertainment, "promised" to release them if the maplers fight against his general Magnus and win. the battle takes place in front of the throne like a sort of arena