The Impediment Jinx

A jinx that stops or slows down people or creatures, Impedimenta temporarily immobilises an attacker offering the spell caster a chance to escape. As this spell causes minimal damage it is commonly taught in schools, including in Hogwarts' Duelling Club. Although the jinx is effective against most animals and people, it can be useless against armoured creatures such as Acromantula, Blast-Ended Skrewts, or beings that do not hold a physical corporeal form such as Lethifolds. Harry taught the spell to the members of Dumbledore's Army during their secret lessons.