2 heads filled with tear-your-hair-out difficulty.
I don't want to give away a lot with this battle, because it's just to damn awesome. All I can say is this: using your grappling hook in new, inventive ways (slingshotting his atacks back at him!?!?! dragging his face into a platform by grappling his tongue?!?!?), this is just the perfect cap on the perfect level. If you haven't played this game, go do so now, if only to play what I believe to be one of the best Zelda dungeons ever.