This Harry Potter heat changing mug is sure to cast a magic spell over your morning brew. Cold, the mug shows Voldemort’s Dark Mark and the famous words ‘He who must not be named’. When hot liquid is poured in, the mug transforms to reveal Lord Voldemort himself casting the Avada Kedavra spell – the Killing Curse. Once the drink is finished the mug returns to its original state as it cools. An essential for any Harry Potter display.