I've been working a bit on writing out the dramas. I haven't made a lot of progress yet though, and I decided to start on chapter 17, the second to the end. I don't know why.
But I can comment on some differences in the events concerning the ending.
The party (Edit: for reference sake, Alex, Nash, Mia, Jessica, and Kyle) flies to the Goddess Tower on Nall's back. Xenobia is waiting for them when they arrive, and the other party members tell Alex to go into the Tower ahead of them while they keep Xenobia busy.
Alex encounters Black Luna at the top of the Tower, followed shortly by Ghaleon, who has some information to share: First, Luna is no longer a human or a goddess, but simply a pawn of his new order; Second, he has fatally wounded Laike (Ghaleon confronted the party and Laike in chapter 16); and finally that without his intervention, the magic that sustains Lunar will die with Luna. Alex disputes this, and not long afterwards the fight is on.
Back with the party and Xenobia, things are looking grim for our heroes. Xenobia casts a big fire spell, and Nall shields the others. Apparently this sacrifice was all they needed to turn things around.
Nash (of all people) delivers the final blow to Xenobia.
The witch is down but not out, however. She asks a seriously wounded Nall why he would assists humans other than the Dragonmaster. Nall gives the obvious answer, "Because they're my friends." Xenobia laughs bitterly at this, and tells the party that she'll take them down with her. She casts one final, terrible spell...
And we switch back to Alex and Ghaleon. Ghaleon has the upper hand, and tells Alex that as long as he cannot swear loyalty to Althena, he will never be able to weild Althena's Sword. And since Luna is under his control, that will never happen. Alex thinks back to a conversation he had with Luna (from the begining of the drama series, I'd imagine,) where he swore on the Blue Star that he would protect her. After a bit of drama Alex succeeds in drawing Althena's Sword, much to Ghaleon's shock.
And then the fight begins in earnest, to be continued in the final chapter.
...As you can see, it's a little crazy, but not nearly as crazy as the novels.