This is an actual spoiler, so read at your own risk. [spoiler] In Halo escalation, The Master Chief and Blue Team confront the Didact, and long story short he ends up being composed at the Composer's Forge. It is currently unknown [i] how[/i] he was composed because it is stated he is immune to the effects of the composer, however when he was fired directly at by 6 composers at the Composer's Forge, he was somehow still composed[/spoiler] I don't have the answer as to how or why it happened, but it'll probably have a pretty large plot significance later on in the story.