The first potion that came to mind for Ariadne was the Polyjuice Potion, which, as she had read somewhere, required leeches as an ingredient. Raising her hand, the girl replied: 'For a potion as the Polyjuice Potion, leeches are needed. These can be found in water, so there would probably be some in the Black Lake.' Only the thought of that made her shudder, especially at the thought that she'd actually considered going for a swim in the lake.