The current study is the first to attempt to perform a sound-symbolic analysis of the spells featured in the Harry Potter series. The present research analysed 171 spells in terms of syllable lengths and the number of voiced obstruents and stressed low vowels. The results showed that the Killing Curse, Avada Kedavra, which is known as one of the most powerful and sinister spells, has the most voiced obstruents and stressed low vowels. The study then experimentally examined whether three factors – syllable lengths, voiced obstruents and low vowels – evoked the imagery of powerful spells using nonce words. The results suggested that voiced obstruents and stressed low vowels are sound-symbolically associated with powerful imagery, which aligns with the studies in Pokémonastics concerning strong character names (Kawahara et al. 2018; Shih et al. 2019). Moreover, names containing more syllables were favoured as powerful spells by those who are unfamiliar with the Harry Potter series, which is evidence of the iconicity of quantity in general English speakers.