Interesting thought process. You had an idea to lessen the required effort only to talk yourself out of it while implementing it. It happens.
As for the placeholder, it probably didn't help that illusions look like that in DotA and Warcraft 3, but tinted blue instead of green. That probably helped condition people towards that interpretation.
Also, I'm still a little confused about the fairies. Is the summoned fairy some sort of construct that only lasts for a level, a merry fairy that was at a different location and got teleported in, or a fraction of the original witch fairy contained within the marble?