Patronus Charm
Cast with the incantation Expecto Patronum, this is the defence against Dementors: the caster holds to a powerful happy memory and produces a guardian of silver-white light that drives them back.
The Patronus Charm, cast with the incantation Expecto Patronum, is the recognised defence against Dementors. The caster fixes on a single powerful happy memory and holds it while speaking the incantation, and if the memory is strong enough the wand produces a Patronus: a shape of silver-white light that Dementors cannot touch or feed upon, and which drives them back. A weak or half-formed attempt yields only a shapeless cloud of silver mist. A fully formed, or corporeal, Patronus takes the shape of an animal, different for every witch or wizard, and is considerably harder to produce. The charm sits well beyond ordinary school work.
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