L'Anarchiste for this. Not just because of the name. It definitely has a rather sickly aura to it, especially in the topnotes. It reminds me of medicines and clean metal in an operating room. AND it's sickly sweet. Justy what you're looking for, in terms of the costume. The problem is, it isn't good for much else, IMO. So you might just get a decant of it. Because it would be a perfect zombie smell.