A novelisation (perhaps better termed a cross-promotional tie-in loosely related to the original property) of the game was produced by Byron Preiss (with a grey-striped cover design emulating Infocom game packaging), published by Avon Books. It was written by Craig Shaw Gardner and first published in August of 1988. Its ISBN is 0-380-75385-5 and the rear cover blurb reads as follows:
"The field needs more humorists of this caliber." - Robert Lynn Asprin
Wishbringer's box and content were already finished before Brian Moriarty even started programming.
The interesting thing about the Wishstone that separated it from other glow in the dark goodies of the day is that it actually glows purple - quite unusual! (and, as a side note, I still have mine and 15+ years later, it still glows perfectly)
A small number of grey-box releases of this game were sold without the plastic glow-in-the-dark stone, and without it being mentioned in the contents list on the back (I have one myself). These were most likely a very late release of the game, right before Activision took over. Reissuing the box must have been cheaper than manufacturing more of the plastic toys once the original supply ran out.
In my experience, this is one of the most (if not the most) early game to use documentation as a way of confirming that you had the original. Those of you who owned games in the late 80s and early 90s know what I mean. It consisted of this: in one point in the game, you find a letter that you can't read onscreen; the game mentions that it is included with the original package. Although the game didn't seem to formally use this letter as copy protection, you missed an important part of the game.
Wishbringer came with a "wishstone", a white stone with a pale, almost indiscernably green cast to it. It glowed in the dark, too.