Hecate didn't speak, as she looked at Evelyn. She was pondering what the headmaster would think of her for answering the child's question. She rationalized it as she wasn't technically teaching her the potion, she was merely confirming something the girl would end up reading in the restricted section, if and when she ever got a chance to go there, as she, Hecate, had done so many years ago. This was theory and she was a professor. "Miss Fl-Shepard," that was going to get annoying, "there are indeed such potions. The counter-potion, however, needs to be administered twice a day for an entire week before the effects of the original potion are annulled." He said, "These potions aren't used very often. They are a longer, more expensive, not to mention more complicated version of their unforgivable curse counterpart..." Though the potion was more effective than the curse, Hecate wasn't going to tell her that.