Spoiler New Art Reveals Two Upgraded Bows and Late Game Villian

[Zorth]

I'm reasonably sure that the new guy is a form of the Imprisoned, but that's not to say he's the final form. If this is indeed Ghirahim's master, I see him transforming into a third form, complete with the horns seen in the intro.

Very possible, Kind of like when Ganondorf transforms into GAnon in OoT..
But this form does look a bit final, The Sword, The Monstrous look it seems like he's already taken a beating and transformed for one final time if you ask me.. :/