Nose is mage-street for Gnosis. Nose is a drug that results in short-lived ecstatic feelings with terrible side effects. Each usage of Nose results in increased risk of paradox for the user, with the effects slowly fading after many months.
Nose is distilled from the souls of mages harvested while they were still alive.
Disturbingly, this drug, introduced by alton_whitehead through the_chantry, stubbornly refuses to disappear completely. It is unknown whether doses have are newly manufactured, or some lingering artifact of Alton's handiwork.