The Drachnor Campaign
A narcotic used among many Imperial subjects (cocaine essentially).
Those taking obscura enter a dream-like state for 1d5 hours (if required to engage in combat consider them under the effects of a hallucinogen grenade). Then for 1d10 hours after the effects wear off, they enter a deep depression, unless another dose of obscura is taken.
While Prohibited and the subject of widespread crackdowns, obscura remains widely used amongst the different subjects within the Imperium. Smugglers can often make a good living importing and selling the drug to all classes of civilians and military personnel.