Was it ever stated what malistaire originally needed from the tower? I remember he had told Ambrose that he already had it but it was never stated. I would it would be bartleby's eye but didn't he steal that when he originally sent the death school flying? Any guesses?
I assume it was some kind of information or book detailing on the Order of the Fang, since you find out that Malistaire was after the Krokonomicon while you're in Krokotopia, which is right after WC. His actions that cause most of WC's areas to end up in chaos that you have to go through could be to distract Ambrose while he's trying to find the Order of the Fang.