The process of making potions wasn't just rigid or strict. It was an art, and he was like an artist drawing a masterpiece.
With each potion he made, he discovered a trait of this toxin. Slowly the entire picture revealed itself to him. "So… It can destroy spirit power inside anything, slowly weakening anyone and adding a sense of illusion of being overly weak… It also affects the spirit and spirit elements, making anyone infected with it unable to exert his full power while using any technique…"
William grabbed the main features of this toxin. It wasn't that deadly, provided that no one got contracted to it for long enough. Its main lethal feature was the weakening effect for any master, making anyone vulnerable and quite weak and powerless against any foe.
William knew to overcome this, the right method was by using some sort of stimulus. He had tons of potions in his head, ones that could turn anyone berserk and crazy.