You know that there is no such thing as magic. Nope, none at all. There is no such thing as a magician, for there is no such thing as magic. Magic is just a made up story to enchant children.
How did mr. Mistoffelees, then, bring Old Deuteronomy back? Simple. After Macavity attacked Munkustrap chased him around and got Old D back. They hid him the pipe and put off a big show for the kits.
How do I know magic isn't real? Well,
I was there,
I saw,
and I am, The Magical Mr. Mistoffelees.