Protego Diabolica

"Play by the rules! No cheating, children!"

- Grindelwald to the Aurors attempting to flee from his spell

Protego Diabolica is the incantation of a powerful protective dark charm. It allows the user to conjure a protective ring of black fire around them. In 1927, Gellert Grindelwald cast this spell in the Lestrange Mausoleum to test the loyalty of his followers and kill a number of his enemies.

Casting and effects
When cast, Protego Diabolica creates a ring of black fire around the caster. It is possible to walk through the flames unharmed, as demonstrated by Queenie Goldstein and Abernathy amongst others, if they are loyal to the caster and mean them no harm. However, Krall, who earlier expressed doubt about Grindelwald's goals, was burnt to ash within a few moments of entering the fire.

Grindelwald was also seen controlling the spell as a weapon by causing tendrils of black fire to extend from the ring and burn his enemies, some of whom were in the process of apparating. The tendrils can be deflected or blocked, temporarily, with the Shield Charm.

Grindelwald was able to use the ring of fire in an attempt to destroy Paris. He conjured what appeared to be a fiery winged demon that spread and burnt everything in sight. It was so powerful that it required the combined usage of the General Counter-Spell by Newt and Theseus Scamander, Tina Goldstein, Nicolas Flamel and a number of others.

Etymology

 * The incantation comes from Latin "protego", "I protect", and "diabolica", a declension of "diabolicus", meaning "diabolic, relating to the Devil".

Behind the scenes

 * In 🇨🇬, the spell creates a "circle of black fire", whereas in the film the flames are bright blue.

Appearances

 * Harry Potter and Fantastic Beasts: A Spellbinding Guide to the Films
 * Harry Potter and Fantastic Beasts: A Spellbinding Guide to the Films
 * Harry Potter and Fantastic Beasts: A Spellbinding Guide to the Films

Notes and references
Protego Diabolica Protego Diabolica