Little Magic Shop of Horrors - A novel by A G Cascone(The sixth book in the Deadtime Stories series)
(1996)
Peter buys a magic kit in a strange little magic shop and becomes 'Peter the Great.' Now he can do tricks even Houdini couldn't perform! The only problem is, Peter can't undo the tricks. But that doesn't bother him too much. Not until he wins the talent show-by taking off his best friend's head!