Salt Zombis
As everybody knows (for given values of ‘everybody’): if you’re facing a Caribbean Voudon-style zombi, and you give it salt, the taste of it suddenly reminds the zombi that it’s dead (or drugged, or possessed, or whatever the cultural meme is this week*). And that shuts the zombi down. Which is great! Wonderful! Well done, ye fearless counter-occult specialists.
Only, what happens to the salt afterward?
Well, it won’t ‘just get washed down the drain,’ actually. Salt that’s been used to shut down a zombi isn’t used-up magical material; it’s primed magical material. There’s a massive symbolic payload in used zombi salt; nobody was going to simply throw that stuff out without checking whether it could be used for something.
And it turns out it can be! Specifically, the salt can be used as the main ingredient in a potion that will turn a person into a zombi temporarily; one dose lasts for about a day, and during that time the subject will register as a zombi on every known mundane and occult test. The only real difference is that the subject will not be under the control of anyone during that time period, but will still know what a ‘proper’ zombi would do in any given situation.
Put another way: if somebody wanted to infiltrate a zombi plantation or factory for some reason, a Salt Zombi potion is the way to do it. The only problem is that anyone who uses a Salt Zombi potion regularly may be more susceptible to being turned into an actual zombi using the usual methods. Worse: if they do become a ‘normal’ zombi, then the regular salt cure might not work on them. Things can get very meta at that level of symbolic relevance…
*What? You thought that esoteric engineers are somehow magically (ahem) immune to the influences of modern pop culture? …Well, they’re not.