A Shield Charm is used to protect the spell caster with an invisible shield that can deflect a spell back at an attacker, or else weaken stronger spells. Protego can be used to protect the individual whilst alternative spells, such as Protego Totalum, can be used for a wider area and the individuals within it. A relatively difficult spell to cast, the members of Dumbledore’s Army nevertheless mastered it in an effort to protect themselves against attacks by Lord Voldemort and his followers.