Harry Potter Marauder\'s Map Heat Changing Mug Step into the wizarding world of Harry Potter with this beautifully designed heat changing mug. Perfect for any fan of the Harry Potter franchise, the mug displays the famous message ‘I solemnly swear I am up to no good’ on the front, while the back shows footprints leading around the side. The inner base of the mug has the words ‘Mischief Managed’ written in the same stunning scripture displayed on the front. Once the mug is filled with hot liquid, the ‘Marauder’s Map’ is revealed showing the entire design of the Hogwarts castle and grounds. Packaged in a Harry Potter designed box that features the Hogwarts school logo, the mug would make an ideal gift for fans everywhere.