12 Most Deadly Spells In The Harry Potter Universe

10. Protego Diabolica

Say what you want about Grindelwald, but he was the world's most renowned Dark Wizard for a reason: his mostly unparalleled powers. Yes, he preferred to have his minions do his dirty work, but that's only possible when you become so powerful you don't need to prove it.

In Fantastic Beasts 2, we got to see the extent of those powers thanks to his conjuring of Protego Diabolica in the Lestrange Mausoleum. To test the loyalty of his followers, he casts a circle of blue fire (black in the script, which would have been way cooler) and demands they cross it. Those who don't "pass the test" are instantly and painfully burnt to ash.

Despite its name, though, it's not just a protective charm and can be controlled like Fiendfyre, including being formed into bestial projections in order to attack and burn enemies alive. No wonder it's got such an ominous name.