'Useful' is definitely far too broad a category of things to be ... well, useful, but Daud won't say as much. What Strange clarifies it with isn't much of a surprise at all, either.

"I'll keep you apprised," he answers, "Though I don't think I'll be returning there soon." Mostly because there's already so much crap on his plate in this city alone; Daud wants answers, but he's not running off a second time.

"You've already had a look at that book with the ritual, haven't you?"