Phlebotinum defined… but not etymologized

A Wiki cataloging of TV molecules. Okay, “Television Tropes, Idioms and Devices.” Among them, Phlebotinum, which I am under the impression was coined by the Buffy the Vampire Slayer writing staff.
(later: sorry, I’m dumb, lots of this stuff is from the Jossverse- it’s from Buffista org people.)
I must say, I know more than one person who will read this who could probably write a pretty definitive guide just on their own. And perhaps should. I’ll help with the research and footnotes.