Siri has three built-in Harry Potter spells that can be used on an iPhone: Lumos, Nox, and Accio. Lumos turns on the flashlight, Nox turns it off, and Accio opens an app. To use these spells, activate Siri and say "Hey Siri" followed by the spell name. For example, to turn on the flashlight, say "Hey Siri, Lumos". To turn it off, say "Hey Siri, Nox". To open an app, say "Hey Siri, Accio . It is also possible to create custom spells using the Shortcuts app. While there are only three built-in spells, there are at least ten Harry Potter spells that work with Siri.