Achievements in Charming is a charms spell book, useful for studying for the Theory of Charms O.W.L.
Has quite sharp edges, as Harry learnt when Hermione kept snatching it away from him to "check that she had got the answer completely right" while he was testing her the day before their Theory of Charms O.W.L. (OP31).
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"Achievements in Charming" on the Harry Potter Wiki