While shouting that and zipping the Maguss Wand around in your friend's face won't quite make him levitate like it would in the Harry Potter universe, it could cause him to skip a turn and let you make your getaway.
The Maguss Wand is a new gizmo whose makers recently launched a Kickstarter campaign in an effort to bring wizarding competition into real life.
It consists (naturally) of a wand, as well as wearable target sensors and an app that goes on your smartphone. The app contains various spells that you can execute with the wand by moving it around in the correct pattern. Wave the wand around in the pattern for a lightning bolt spell for example, and if another player is within range, you'll cause her damage. Cause enough damage and you'll be the winningest wizard in the world (well, at least in your 'hood).
You earn more spells as you level up, and each one triggers a different sound on your opponent's smartphone, so there's no need to keep pulling out your phone to figure out what's going on in the game.
Despite the fun this all seems like, the campaign is a bit slow to get off the ground, but it is still early days, with over a month to go.
So far, the campaign has raised just over $2,000 for a goal of just over $66,000 (prices on the site are in Danish Krones). It's still early days though, with over a month left in the campaign. If you're interested in pledging, you can get a wand and the app for roughly $66 (about £43, AU$89).
Otherwise you can just try waving your wand at the checkout screen to see if you can get one for free. I believe the incantation is Iwantius libertas!