Louisa pondered the question for a moment.

And another.

Another one.

She started uncertainly, unable to stay still when she had nothing in mind, "Umm... I think during one of the darkest time in Magic History that boy with a scar used it to try and destroy one of the heckroxes*." She didn't remember how, why, whether it worked or not... it just stuck to her Ravenclawish mind because it was the first time she ever heard of Diffindio.

OOC: *Heckroxes = Horcruxes in Louisa's failing memory