OH MY GOD.
Though I must say, that whole episode was big fucking amazing explosion. Guessing that's what the title was referring to.
( Couple of spoilers, though you've all probably heard already anyway )Guessing at the last major battles for people:
Setsuna -> Graham
Lockon -> Ali*
Allelujah -> Andrei*
Tieria -> Ribbons, Regene
Saji -> Louise
The two * I'm wavering on. I really don't think that Ali will be Setsuna's final enemy for various reasons, and Tieria's got enough to deal with (though it would be most satisfying and just if he was the one to kill him), so I'm guessing it will be Lockon. He wrote his brother's death off as absurd, but it was clear how shaken he was by meeting the man who killed him. That and Ali is tied up in a lot of Anti-Kataron business, which gives Lyle another reason to go after him.
Andrei could get killed off by either Allelujah or Soma. Though Soma would be more appropriate, I'm leaning towards Alle, probably even Halle. And not just because he's the only hero without a major enemy. XD I suspect that if Soma doesn't emerge again, Marie will pretty much be very similar to her and grow distant from Alle. She'll go on some hell-bent vengeance and get herself in trouble and Allelujah will have to help her. OR what I find to be more likely is that she'll get killed and Hallelujah will return, go ballistic, and kill Andrei. Because I still hold that Allelujah and Marie have had too much happy-time and therefore something bad must happen by Gundam standards. And her not being in the opening sequence of the song and Allelujah reaching forward and crying out is a little telling.
Though judging my comments I've seen, this episode has put faith back in a lot of people's minds over season two, which is a good thing. It was a damn good episode.