This is set in the same (set of) universe(s) as "Horse Trading", posted independently.

"Halfa Loaf..."

The prophecy was in one of the ancient books salvaged from the old Watcher's Council library. Written in Lepontic, it had been partially translated; even so it had taken quite some time to finish.

Giles sighed, polishing his glasses. He really didn't know what to make of it.

The darkest power of the forlorn
Fighting she who was not born
The girl both dead and alive
Helping fight the wicked lies
Neither flesh or spirit full
But will destroy the evil pull

Who was it referring to? He hoped they could find out before it blew up in their faces.

Joss Wheldon was the mastermindbehind Buffy the Vampire Slayer.