Severus Snape: "This is your copy of Advanced Potion-Making, is it, Potter?"
Harry Potter: "Yes."
Severus Snape: "This is the copy of Advanced Potion-Making that you purchased from Flourish and Blotts?"
Harry Potter: "Yes."
Severus Snape: "Then why does it have the name ‘Roonil Wazlib’ written inside the front cover?"
Harry Potter: "That’s my nickname."
— The effects of the quill deteriorating over time[src]
A Spell-Checking Quill is a magical type of quill enchanted to correct an individual's spelling errors. As the charm's potency decreases over time, its effects may backfire, leading to correctly spelled words becoming misspelled.


During the 1995-1996 school year, these were banned from Hogwarts School of Witchcraft and Wizardry by Professor Dolores Umbridge, following the creation of Educational Decree Number One.

They were sold by Weasleys' Wizard Wheezes in 1996, where Ronald Weasley purchased one. However, the charm on the quills wore off after several months, resulting in even worse spelling than before.

Behind the scenes

  • It appears that when the charm wears off it results in worse spelling than before, as Ron's homework was left with terrible misspellings: "belligerent" starting with "bum" and "augury" with "org", as well as "Dementors" as "Dugbogs", and his own name became "Roonil Wazlib".
    • Ironically, the misspelled name "Roonil Wazlib" partially saved Harry Potter from being condemned for using the cheating notes textbook when Harry used Ron's textbook to pass the inspection, as when Severus Snape checked Harry's books, the name in the book has changed enough for Harry to claim it was his nickname (even though Snape clearly saw through the façade, he lacked the evidence to outright contradict Harry).


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