Defensive spells

Defensive spells are a certain type of spell that can be used in a duel.

Spells
Stupefy, or the Stunning Spell, is perhaps the most common Charm used in a duel. Its effects (says in the name) stuns its target, sometimes knocking the person or object through the air!

Protego is the most common blocking spell, also known as the Shield Charm.

Used in...
Duels,

Dementor attacks.