I have read the first four and love it, if you enjoyed these books defo check out my listamania and in particular The Elements of Lore and the Bartemeous triology!! I find the prologue in all the Spook's books very ominous aka Tom is done for!
I have juts finihsed the 5th book and I loved it. I think that eventually Tom will die though and that is why at the beginning the place where the fiednw ill eventually be defeated is called the wardstone, as in Tom Ward. If you are hankering after some other books to read you should try The Elements of Lore by Harry S Hope, kicks off an excellent series.
This series is brilliant!! As regards the Wardstone Lore(as I call it), it would seem to be referring to Tom dying whilst binding the Fiend, but it could possibly be the Spook dying, whilst Tom (and Alice, perhaps) actually bind the fiend, therefore giving the Wardstone it's name.