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Nightweed is an illegal poison that even masks are not allowed to use. It was outlawed a century before A Torch Against The Night takes place, after it was used to assassinate an Emperor. It is always deadly, though in higher doses, it kills swiftly. In lower doses, the only symptom of the poison are severe seizures. Nightweed is the poison used by the Commandant to poison Elias. She delivered a low dose by slicing him with a dagger and subsequently let him go.