As Potter fans know, magic doesn't get much tougher than the Patronus charm - but now, even Muggles can manage that most difficult of spells, thanks to a new online tool.
Harry Potter creator J.K. Rowling has unveiled the latest addition to her wizarding world - a quiz that helps fans to find their spirit guardian.
The author directed fans to her Pottermore website to take a Patronus test, which refers to one of the spells she wrote about in the series of children's books, a complex charm said to conjure up a creature to act as a ghostly protector for her magical characters against evil beings the Dementors.
Rowling tweeted about the new website feature, telling followers which guide she had been assigned.
She told a fan who asked what it was: "It's a heron :)"
The website guides visitors through a quiz in which they are asked to think of their happiest memory and then choose from lists of words the one that stands out to them the most, before it generates a spirit creature.
Rowling's Patronus storyline featured in her book Harry Potter And The Prisoner Of Azkaban, where the student wizard discovered his Patronus was a stag, under the direction of tutor Remus Lupin who called on a wolf as his own protector.
The Patronus Test is available at www.pottermore.com.