And I doubt you want heroin to save you. As we all learned from our favorite after-school specials, drugs aren't the way to go when you want something done. Especially in this case, when you're hoping to be saved from an oncoming apocalyptic comet or evil be-tentacled demons--I imagine it would rather suck if your hopes rested on a pile of unaided mind-altering substances. Maybe if Captain Trips were involved, you could be saved by the intervention of a drug cocktail. But not if the heroin is just sitting there in a neat little pile or in a little hypodermic needle.
Context is amused.