During Tengen Toppa Gurren Lagann: Lagann-hen (the second movie), the protagonists encounter Granzeboma at about 01:32:30 into the movie, and a battle begins. (A clip of the scene can be found here; the music begins about 10 seconds in.)
I've listened to as many of the songs in the OST as I can find, and none match this noble, battle-laden theme. What music is it that plays during this scene? Is it even available?