Walk around the commons of Cambridge and you’re bound to see one or more of the Cambridge University Quidditch Club players mounted upon sticks with a makeshift quaffle. But try as they might, their broomsticks will never send them soaring through the air.

The same faux-wizardry charge can’t be levelled at Allen Pan‘s Real-Life Wizard Duel. For when the wand-wielding witches or wizards cast one of four Harry Potter spells, their opponent is struck accordingly… as if by magic.

Real spells, real consequences

Allen uses Transcutaneous Electrical Nerve Stimulation (TENS) machines to deliver the mighty blows to both himself and his opponent, setting off various sticky pads across the body via voice recognition.

The Google Cloud Speech Recognition API recognises one of five spells – Expelliarmus, Stupefy, Tarantallegra, Petrificus Totalus, and Protego – via a microphone plugged into a Raspberry Pi.

When the spell is pronounced correctly and understood by the Pi, it tells an Arduino to ‘shoot’ the spell out of the wand via an infrared LED. If the infrared receiver attached to the opponent recognises the spell, it sets off the TENS machine to deliver an electric current to the appropriate body part. Expelliarmus, for example, sets off the TENS connected to the arm, while calling out a successful Petrificus Totalus renders the opponent near immobilised as every pad is activated. For a moment’s rest, calling out “Protego” toward your own infrared receiver offers a few moments of protection against all spells aimed in your direction. Phew.

“But people only die in proper duels, you know, with real wizards. The most you and Malfoy’ll be able to do is send sparks at each other. Neither of you knows enough magic to do any real damage. I bet he expected you to refuse, anyway.”
“And what if I wave my wand and nothing happens?”
“Throw it away and punch him on the nose,” Ron suggested.
Harry Potter and the Philosopher’s Stone

Defence Against the Dark Arts

To prevent abuse of the spells, each one has its own recharge time, with available spells indicated via LEDs on the wand.

In the realm of Harry Potter fan builds, this has to be a favourite. And while visitors to The Wizarding World of Harry Potter may feel the magical effect of reimagined Butterbeer as they wander around Hogsmead, I’d definitely prefer to play Real Life Wizard Duel with Allen Pan.